Understand Absolute Value Concept

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6th Grade Math › Understand Absolute Value Concept

Questions 1 - 10
1

During a science experiment, three measurements were recorded: $$-18$$, $$25$$, and $$-7$$. If a fourth measurement $$z$$ is added such that $$|z|$$ is greater than the absolute value of exactly two of the original measurements, what could be a possible value for $$z$$?

$$z = 5$$ works because $$|5| = 5$$, which is less than two measurements but positive

$$z = 30$$ works because $$|30| = 30$$, which is greater than all three original measurements

$$z = 10$$ works because $$|10| = 10$$, which is greater than $$|-7| = 7$$ and $$|25| = 25$$

$$z = 20$$ works because $$|20| = 20$$, which is greater than $$|-7| = 7$$ and $$|-18| = 18$$

Explanation

When you see a problem about absolute values and comparisons, remember that absolute value measures distance from zero, ignoring the sign. So $$|-18| = 18$$, $$|25| = 25$$, and $$|-7| = 7$$.

The question asks for a value of $$z$$ where $$|z|$$ is greater than exactly two of these absolute values: 18, 25, and 7. This means $$|z|$$ should be greater than two values but not all three.

Let's check each option systematically. For choice B, if $$z = 20$$, then $$|z| = 20$$. Comparing this to our original absolute values: $$20 > 7$$ (true), $$20 > 18$$ (true), and $$20 > 25$$ (false). So $$|20|$$ is greater than exactly two of the original absolute values, which matches our requirement perfectly.

Choice A claims $$|10| = 10$$ is greater than both 7 and 25, but $$10 < 25$$, so this comparison is incorrect. Choice C states that $$|30| = 30$$ is greater than all three measurements, which violates the "exactly two" requirement. Choice D suggests $$|5| = 5$$ works, but 5 is only greater than 7, not two values, and the reasoning about being "positive" is irrelevant to absolute value comparisons.

When working with absolute value comparison problems, always convert negative numbers to their absolute values first, then systematically check each condition. The key word "exactly" means you need to count precisely how many comparisons are true.

2

On a number line, point $$P$$ is at $$-7$$ and point $$Q$$ is at $$3$$. If point $$R$$ has the same absolute value as point $$P$$, which of these could be the location of point $$R$$?

Point $$R$$ could be at $$7$$ or $$-7$$, but since $$P$$ is already at $$-7$$, then $$R$$ is at $$7$$

Point $$R$$ must be at $$-7$$ because that's the only location with absolute value $$7$$

Point $$R$$ could be at $$3$$ or $$-3$$ since those have the same distance relationship

Point $$R$$ must be at $$0$$ because absolute value measures distance from zero

Explanation

When you see a question about absolute value on a number line, remember that absolute value measures the distance from zero, regardless of direction. Two different points can have the same absolute value if they're the same distance from zero on opposite sides.

Point $$P$$ is at $$-7$$, so its absolute value is $$|-7| = 7$$. This means $$P$$ is 7 units away from zero. For point $$R$$ to have the same absolute value, it must also be exactly 7 units from zero. There are only two positions that are 7 units from zero: $$-7$$ (where $$P$$ already is) and $$+7$$. Since the question asks where $$R$$ could be, and $$P$$ is already at $$-7$$, point $$R$$ must be at $$7$$.

Choice A is wrong because absolute value doesn't put points at zero—it measures distance from zero. Choice B incorrectly assumes only negative numbers can have absolute value 7, but both $$7$$ and $$-7$$ have absolute value 7. Choice C uses the wrong reference point; it considers distance relationships with other points rather than distance from zero, which is what absolute value measures.

Choice D correctly identifies that both $$7$$ and $$-7$$ have absolute value 7, and since $$P$$ occupies $$-7$$, point $$R$$ must be at $$7$$.

Study tip: Remember that absolute value creates pairs—for every positive number, its negative counterpart has the same absolute value. When solving absolute value problems, always consider both the positive and negative possibilities.

3

A submarine's depth is recorded as $$-45$$ meters, and a mountain peak's height is $$28$$ meters above sea level. Which statement correctly describes the relationship between their absolute values?

$$|-45| > |28|$$ because the submarine is farther from sea level than the peak

$$|-45| < |28|$$ because negative numbers are always smaller than positive numbers

$$|-45| < |28|$$ because the absolute value of depth must be less than height

$$|-45| = |28|$$ because absolute value makes all numbers equal to zero

Explanation

$$|-45| = 45$$ and $$|28| = 28$$. Since $$45 > 28$$, the submarine is farther from sea level (45 meters) than the mountain peak (28 meters). Choice B confuses absolute value with comparing the original numbers. Choice C misunderstands what absolute value means. Choice D incorrectly assumes a relationship between depth and height absolute values.

4

In a video game, a character can move above or below a reference line. The character's current position is $$-15$$ units from the reference line. If the character moves to a new position that is the same distance from the reference line but on the opposite side, what calculation represents this move?

The new position is $$|-15| = 15$$ units from the reference line on the opposite side

The new position is $$-|-15| = -15$$ units, which is the same as the original position

The new position is $$15 - (-15) = 30$$ units from the reference line

The new position is $$|15| = 15$$ units, calculated from the positive distance only

Explanation

When you see a problem about positions relative to a reference line, you're working with integers and absolute value. The key insight is understanding that distance is always positive, while position can be positive or negative depending on which side of the reference line you're on.

The character starts at $$-15$$ units, meaning it's 15 units below the reference line. When it moves to "the same distance but on the opposite side," it goes to 15 units above the reference line. The absolute value $$|-15| = 15$$ gives us the distance (15 units), and since we're moving to the opposite side, the new position is $$+15$$ units from the reference line.

Choice A is incorrect because $$15 - (-15) = 30$$ calculates the total distance traveled during the move, not the final position. While the character does move 30 units total, its final position is only 15 units from the reference line.

Choice B is wrong because $$-|-15| = -15$$ would put the character back at the original position, not on the opposite side as required.

Choice D misses the point by starting with $$|15|$$ instead of $$|-15|$$. The problem specifically states the original position is $$-15$$, so we need to find the absolute value of that negative number.

Remember: absolute value always gives you the distance (positive number), and when a problem asks for the "opposite side" of a reference point, you're looking for the same distance but with the opposite sign from where you started.

5

Elena's bank account shows a balance of $$-\32$$. She wants to find how much money she needs to deposit to have a balance of $$\0$$. In terms of absolute value, what does she need to calculate?

She needs to calculate $$|-32| + |0|$$ to find the total distance

She needs to calculate $$|-32|$$ to find the magnitude of her debt

She needs to calculate $$|32|$$ since she owes a positive amount

She needs to calculate $$-|-32|$$ to account for the negative balance

Explanation

When you encounter problems involving negative bank balances or debts, think about absolute value as a tool for finding the "size" or "magnitude" of a number, regardless of whether it's positive or negative.

Elena has a balance of $$-\32$$, which means she owes the bank $32. To get to a balance of $0, she needs to deposit enough money to cover exactly what she owes. The absolute value $$|-32|$$ gives us the magnitude of her debt, which is $32. This tells her exactly how much she needs to deposit.

Let's examine why the other choices miss the mark. Choice A suggests calculating $$-|-32|$$, which equals $$-32$$. This just gives us the original negative balance again, not the amount needed to deposit. Choice B says to calculate $$|32|$$, but Elena's balance isn't $$+\$32$$—it's $$-\$32$$, so we need the absolute value of the negative number. Choice C proposes $$|-32| + |0|$$, which equals $$32 + 0 = 32$$. While this happens to give the right numerical answer, it's not the correct reasoning—we don't need to add anything to zero.

Choice D correctly identifies that Elena needs $$|-32|$$ to find the magnitude of her debt, which is $32.

Study tip: Remember that absolute value strips away the sign and gives you the distance from zero. When dealing with debts or negative balances, absolute value tells you the actual amount owed, which is what you need to "cancel out" the debt.

6

Marcus is tracking temperature changes in his city. On Monday, the temperature was $$-8°F$$. On Tuesday, it was $$12°F$$. If Marcus wants to know which day had a temperature with the greater distance from $$0°F$$, what should he compare?

He should compare $$8$$ and $$-12$$ since distance can be negative

He should compare $$|-8|$$ and $$|12|$$, so $$8$$ and $$12$$

He should compare $$|-8|$$ and $$|12|$$, so $$-8$$ and $$12$$

He should compare $$-8$$ and $$12$$ directly without using absolute value

Explanation

Distance from 0 is always measured as a positive value, which is exactly what absolute value represents. $$|-8| = 8$$ and $$|12| = 12$$, so we compare 8 and 12. Choice B ignores the concept of distance from zero. Choice C incorrectly states that $$|-8| = -8$$. Choice D incorrectly suggests distance can be negative.

7

Three numbers have the same absolute value: $$x$$, $$-9$$, and $$y$$. If $$x > 0$$ and $$y < 0$$, and $$x \neq y$$, what can you conclude about $$x$$ and $$y$$?

$$x = -9$$ and $$y = 9$$, since absolute value reverses the signs

$$x = 9$$ and $$y = -9$$, but they don't have the same absolute value

$$x = 3$$ and $$y = -3$$, since they must be smaller than $$|-9|$$

$$x = 9$$ and $$y = -9$$, so they are opposites with the same absolute value

Explanation

When you encounter absolute value problems, remember that absolute value measures distance from zero on the number line, regardless of direction. Multiple numbers can share the same absolute value if they're the same distance from zero.

Since all three numbers have the same absolute value, and we know one of them is $$-9$$, we can find that absolute value: $$|-9| = 9$$. This means $$x$$, $$-9$$, and $$y$$ all have an absolute value of 9.

For a number to have absolute value 9, it must be either 9 or $$-9$$ (since both are exactly 9 units from zero). Given that $$x > 0$$, we know $$x = 9$$. Since $$y < 0$$ and $$y \neq x$$, we know $$y = -9$$. Notice that $$y$$ and the given number $$-9$$ are actually the same number, which makes sense since they must have the same absolute value.

Looking at the wrong answers: Choice A incorrectly states that $$x = -9$$, but we're told $$x > 0$$. Choice B correctly identifies $$x = 9$$ and $$y = -9$$, but wrongly claims they don't have the same absolute value—they both equal 9. Choice D suggests $$x = 3$$ and $$y = -3$$, but these have absolute value 3, not 9 like the given number $$-9$$.

Choice C correctly identifies that $$x = 9$$ and $$y = -9$$, and recognizes they are opposites (numbers that are the same distance from zero but in different directions) with the same absolute value.

Study tip: Remember that every positive number has a negative opposite with the same absolute value, and vice versa.

8

A thermometer shows the temperature dropped to $$-12°C$$ overnight. By noon, it had risen to $$8°C$$. Using absolute value, how can you express the total magnitude of temperature change from the lowest point?

The total change is $$|8| - |-12| = 8 - 12 = -4°C$$ directional change

The total change is $$|8 - (-12)| = |20| = 20°C$$ from the lowest temperature

The total change is $$|8| + |-12| = 8 + 12 = 20°C$$ from zero reference

The total change is $$|-12| - |8| = 12 - 8 = 4°C$$ net difference

Explanation

When you encounter temperature change problems, you need to understand what "total magnitude of change from the lowest point" means. This is asking for the absolute distance the temperature traveled from its lowest value to its final value.

The temperature started at $$-12°C$$ (the lowest point) and ended at $$8°C$$. To find the total change from the lowest point, you calculate the difference between the final and initial temperatures: $$8 - (-12) = 8 + 12 = 20$$. Since the question asks for magnitude (absolute value), you write this as $$|8 - (-12)| = |20| = 20°C$$. This shows the temperature moved 20 degrees from its lowest point, which is answer B.

Answer A incorrectly adds the absolute values of both temperatures as if measuring distance from zero separately. While $$|8| + |-12| = 20$$, this doesn't represent the change from the lowest point—it's adding distances from zero instead of measuring the actual temperature journey.

Answer C subtracts absolute values ($$|-12| - |8| = 4$$), which gives you neither the total change nor the correct magnitude. This approach loses the directional relationship between the temperatures.

Answer D attempts to show directional change but makes an error by subtracting absolute values, resulting in $$-4°C$$. However, the question specifically asks for magnitude, which is always positive.

Remember: when finding temperature change between two points, subtract the starting temperature from the ending temperature, then take the absolute value if you need magnitude only.

9

Which statement is true about the numbers $5$ and $-5$?

$|5|=0$ because absolute value measures distance to 5.

$|5|=5$ and $|-5|=-5$.

$|5|<|-5|$ because negative numbers have larger absolute value.

$|5|=|-5|$ because both are 5 units from 0.

Explanation

This question tests understanding of absolute value as distance from zero on a number line, always ≥0 with sign removed, comparing magnitudes of positives and negatives. Absolute value |a| is distance from zero; |5|=5 and |-5|=5, both 5 units away, since negatives flip to positive and positives stay. In comparison, |5|=|-5| because they are equidistant from zero, ignoring signs. An example is |5|=5 (5 units right) and |-5|=5 (5 units left), same distance. The correct statement is |5|=|-5| because both are 5 units from 0, not inequalities or wrong values. Errors include thinking negatives have larger absolute values, keeping signs like |-5|=-5, or mismeasuring as zero. Understanding: opposites have equal absolute values as equidistant; calculating flips negatives; number line shows symmetry; uses for comparing magnitudes; common mistakes claim absolute values can be negative.

10

Use the number line to find the distance from 0 to $-4$. Which expression matches that distance?

Number line: $-6\ \ -5\ \ -4\ \ -3\ \ -2\ \ -1\ \ 0\ \ 1\ \ 2\ \ 3\ \ 4\ \ 5\ \ 6$

$|4|=-4$

$|{-4}|=-4$

$|0|=4$

$|{-4}|=4$

Explanation

This question tests your understanding of absolute value as the distance from zero on the number line, which is always non-negative and removes the sign, and interpreting it as magnitude in contexts like temperature deviation from freezing, elevation from sea level, or debt amount. Absolute value |a| means the distance from zero on the number line, so |−7|=7 represents 7 units from 0, just as |-5|=5 is 5 units from 0 and |5|=5 is also 5 units from 0 since the sign doesn't affect distance and both directions yield a positive value; for calculation, a positive number stays the same (|5|=5), a negative becomes positive (|−5|=−(−5)=5 by removing the sign), and zero remains (|0|=0); in contexts, |-15|=15°C shows the magnitude of 15 degrees from freezing point 0°C, |-30|=30 m indicates the magnitude of 30 meters depth below sea level, and |-$50|=$50 represents the magnitude of $50 owed as debt. For example, on the number line from -6 to 6, the distance from 0 to -4 is 4 units to the left, but absolute value gives 4. The correct expression is |-4|=4, matching the positive distance. A common error is |-4|=-4, like keeping the sign, or |4|=-4 confusing positives. Understanding absolute value measures distance from zero, which is always positive because distance cannot be negative, and it removes the sign by making negative numbers positive (|−8|=8) while leaving positives unchanged (|5|=5). To calculate, count units on the number line, apply the rule for negatives, resulting in 4, and remember |-4| and |4| both equal 4 as equidistant.

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