ACT Math : ACT Math

Study concepts, example questions & explanations for ACT Math

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Example Questions

Example Question #96 : Algebra

What is the slope of the line defined by the equation ?

Possible Answers:

Correct answer:

Explanation:

The easiest way to find the slope of a line based on its equation is to put it into the form . In this form, you know that  is the slope.  

Start with your original equation .

Now, subtract  from both sides:

Next, subtract  from both sides:

Finally, divide by :

This is the same as:

Thus, the slope is .

Example Question #731 : Act Math

What is the slope of the line represented by the equation ?

Possible Answers:

Correct answer:

Explanation:

The slope of an equation can be calculated by simplifying the equation to the slope-intercept form , where m=slope.

Since , we can solve for y. In shifting the 5 to the other side, we are left with .

This can be further simplified to 

, leaving us with the slope intercept form.

 

In this scenario, , so slope .

 

Example Question #731 : Act Math

Find the slope of the line  6X – 2Y = 14

 

Possible Answers:

12

-3

-6

3

Correct answer:

3

Explanation:

Put the equation in slope-intercept form:

y = mx + b

-2y = -6x +14

y = 3x – 7

The slope of the line is represented by M; therefore the slope of the line is 3.

 

Example Question #3 : Coordinate Geometry

What line goes through the points (1, 3) and (3, 6)?

Possible Answers:

–3x + 2y = 3

2x – 3y = 5

–2x + 2y = 3

3x + 5y = 2

4x – 5y = 4

Correct answer:

–3x + 2y = 3

Explanation:

If P1(1, 3) and P2(3, 6), then calculate the slope by m = rise/run = (y2 – y1)/(x2 – x1) = 3/2

Use the slope and one point to calculate the intercept using y = mx + b

Then convert the slope-intercept form into standard form.

Example Question #4 : Coordinate Geometry

What is the slope-intercept form of \dpi{100} \small 8x-2y-12=0?

Possible Answers:

\dpi{100} \small y=-4x+6

\dpi{100} \small y=4x-6

\dpi{100} \small y=4x+6

\dpi{100} \small y=-2x+3

\dpi{100} \small y=2x-3

Correct answer:

\dpi{100} \small y=4x-6

Explanation:

The slope intercept form states that \dpi{100} \small y=mx+b. In order to convert the equation to the slope intercept form, isolate \dpi{100} \small y on the left side:

\dpi{100} \small 8x-2y=12

\dpi{100} \small -2y=-8x+12

\dpi{100} \small y=4x-6

Example Question #5 : Coordinate Geometry

A line is defined by the following equation:

What is the slope of that line?

Possible Answers:

Correct answer:

Explanation:

The equation of a line is

y=mx + b where m is the slope

Rearrange the equation to match this:

7x + 28y = 84

28y = -7x + 84

y = -(7/28)x + 84/28

y = -(1/4)x + 3

m = -1/4

Example Question #732 : Act Math

If the coordinates (3, 14) and (5, 15) are on the same line, what is the equation of the line?

Possible Answers:

Correct answer:

Explanation:

First solve for the slope of the line, m using y=mx+b

m = (y2 – y1) / (x2 – x1)

= (15  14) / (5 3)

= (1 )/( 8)

=1/8

y = (1/8)x + b

Now, choose one of the coordinates and solve for b:

14 = (1/8)3 + b

14 = 3/8 + b

b = 14 + (3/8)

b = 14.375

y = (1/8)x + 14.375

Example Question #7 : Coordinate Geometry

What is the equation of a line that passes through coordinates \dpi{100} \small (2,6) and \dpi{100} \small (3,5)?

Possible Answers:

\dpi{100} \small y=2x+4

\dpi{100} \small y=x+7

\dpi{100} \small y=2x-4

\dpi{100} \small y=-x+8

\dpi{100} \small y=3x+2

Correct answer:

\dpi{100} \small y=-x+8

Explanation:

Our first step will be to determing the slope of the line that connects the given points.

Our slope will be . Using slope-intercept form, our equation will be . Use one of the give points in this equation to solve for the y-intercept. We will use \dpi{100} \small (2,6).

Now that we know the y-intercept, we can plug it back into the slope-intercept formula with the slope that we found earlier.

This is our final answer.

Example Question #8 : Coordinate Geometry

Which of the following equations does NOT represent a line?

Possible Answers:

Correct answer:

Explanation:

The answer is .

A line can only be represented in the form  or , for appropriate constants , , and . A graph must have an equation that can be put into one of these forms to be a line.

 represents a parabola, not a line. Lines will never contain an term.

Example Question #9 : Coordinate Geometry

Let y = 3x – 6.

At what point does the line above intersect the following:

 

 

Possible Answers:

They intersect at all points

(0,–1)

(–3,–3)

They do not intersect

(–5,6)

Correct answer:

They intersect at all points

Explanation:

If we rearrange the second equation it is the same as the first equation. They are the same line.

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