ACT Math : ACT Math

Study concepts, example questions & explanations for ACT Math

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Example Questions

Example Question #1 : How To Find The Equation Of A Line

Which of the following is the equation of a line between the points  and ?

Possible Answers:

Correct answer:

Explanation:

Since you have y-intercept, this is very easy.  You merely need to find the slope.  Then you can use the form  to find one version of the line.

The slope is:

Thus, for the points  and , it is:

Thus, one form of our line is:

If you move the  to the left side, you get:

, which is one of your options.

Example Question #2 : How To Find The Equation Of A Line

What is an equation of the line going through points  and ?

Possible Answers:

Correct answer:

Explanation:

If you have two points, you can always use the point-slope form of a line to find your equation.  Recall that this is:

You first need to find the slope, though.  Recall that this is:

For the points  and , it is:

Thus, you can write the equation using either point:

Now, notice that one of the options is:

This is merely a multiple of the equation we found, so it is fine!

 

Example Question #3 : How To Find The Equation Of A Line

Given the graph of the line below, find the equation of the line.

 

Act_math_160_04

Possible Answers:

Correct answer:

Explanation:

To solve this question, you could use two points such as (1.2,0) and (0,-4) to calculate the slope which is 10/3 and then read the y-intercept off the graph, which is -4.

 

Example Question #4 : How To Find The Equation Of A Line

Which line passes through the points (0, 6) and (4, 0)?

Possible Answers:

y = 2/3 + 5

y = 2/3x –6

y = 1/5x + 3

y = –3/2 – 3

y = –3/2x + 6

Correct answer:

y = –3/2x + 6

Explanation:

P1 (0, 6) and P2 (4, 0)

First, calculate the slope:  m = rise ÷ run = (y2 – y1)/(x– x1), so m = –3/2

Second, plug the slope and one point into the slope-intercept formula: 

y = mx + b, so 0 = –3/2(4) + b and b = 6

Thus, y = –3/2x + 6

Example Question #741 : Act Math

Let W and Z be the points of intersection between the parabola whose graph is y = –x² – 2x + 3, and the line whose equation is y = x – 7. What is the length of the line segment WZ?

 

Possible Answers:

7√2

4

4√2

7

Correct answer:

7√2

Explanation:

First, set the two equations equal to one another. 

x² – 2x + 3 = x – 7

 

Rearranging gives

x² + 3x – 10 = 0

 

Factoring gives

(x + 5)(x – 2) = 0

 

The points of intersection are therefore W(–5, –12) and Z(2, –5)

 

Using the distance formula Actmath_7_113_q1gives 7√2 

 

Example Question #742 : Act Math

In an xy-plane, what is the length of a line connecting points at (–2,–3) and (5,6)?

Possible Answers:

9.3

7.5

12.5

11.4

Correct answer:

11.4

Explanation:

Use the distance formula:

D = √((y2 – y1)2 + (x2 – x1)2)

D = √((6 + 3)2 + (5 + 2)2)

D = √((9)2 + (7)2)

D = √(81 + 49)

D = √130

D = 11.4

Example Question #743 : Act Math

Coordinates

What is the distance between points \dpi{100} \small A and \dpi{100} \small B, to the nearest tenth?

Possible Answers:

\dpi{100} \small 5.0

\dpi{100} \small 3.2

\dpi{100} \small 6.4

\dpi{100} \small 7.8

\dpi{100} \small 1.0

Correct answer:

\dpi{100} \small 6.4

Explanation:

The distance between points\dpi{100} \small A and \dpi{100} \small B is 6.4. Point \dpi{100} \small A is at \dpi{100} \small (-2,-3). Point \dpi{100} \small B is at \dpi{100} \small (2,2). Putting these points into the distance formula, we have \sqrt{(-2-2)^{2}+(-3-2)^{2}}=\sqrt{(-4)^{2}+(-5)^{2}}=\sqrt{16+25}=\sqrt{41}\approx 6.4.

Example Question #2 : How To Find The Length Of A Line With Distance Formula

Coordinates

What is the slope of the line between points \dpi{100} \small A and \dpi{100} \small B?

Possible Answers:

\frac{5}{4}

5

\frac{-5}{4}

\frac{5}{2}

-4

Correct answer:

\frac{5}{4}

Explanation:

The slope of the line between points \dpi{100} \small A and \dpi{100} \small B is \frac{5}{4}. Point \dpi{100} \small A is at \dpi{100} \small (-2,-3). Point \dpi{100} \small B is at \dpi{100} \small (2,2). Putting these points into the slope formula, we have \frac{-3-2}{-2-2}=\frac{-5}{-4}=\frac{5}{4}.

Example Question #744 : Act Math

What is the distance between  and ?

Possible Answers:

Correct answer:

Explanation:

Let  and  and use the distance formula: .  The distance formula is a specific application of the more general Pythagorean Theorem:  a^{2} + b^{2} = c^{2}.

Example Question #745 : Act Math

What is the distance, in coordinate units, between the points (-2,6) and (5,-2) in the standard (x,y) coordinate plane?

Possible Answers:

\sqrt{7}

15

\sqrt{15}

\sqrt{113}

113

Correct answer:

\sqrt{113}

Explanation:

The distance formula is \sqrt{((x_{1}-x_{2})^{2}+(y_{1}-y_{2})^{2})}=d, where d = distance.

Plugging in our values, we get

d=\sqrt{((5-(-2))^{2}+(6-(-2))^{2}}=\sqrt{7^{2}+8^{2}}=\sqrt{49+64}=\sqrt{113}

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