ACT Math : x and y Intercept

Study concepts, example questions & explanations for ACT Math

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Example Questions

Example Question #4 : How To Find X Or Y Intercept

Given the linear equation below, what are the x- and y-intercepts, respectively?

Possible Answers:

Correct answer:

Explanation:

To find the x-intercept we will need to plug in zero for the y-value.

The x-intercept will be .

To find the y-intercept we will need to plug in zero for the x-value.

The y-intercept will be .

Example Question #5 : How To Find X Or Y Intercept

At what point do the lines \small y=\frac{1}{4}x+7 and \small y=4x + 7 intersect?

Possible Answers:

(0,-7)

They\ do\ not\ intersect

(0,0)

(0,7)

(7,0)

Correct answer:

(0,7)

Explanation:

Short way:

The lines intersect somewhere because they have different slopes. Because they have the same y-intercept, they must intersect at that point.

Long way using substitution:

\small y=\frac{1}{4}x+7

\small y-7 = \frac{1}{4}x

\small x = 4y - 28

 

Plug this into \small y=-4x+7

\small y=-4(4y-28)+7

\small y=-16y+112+7

\small 17y=119

\small y=7

 

Find \small x

\small x=4(7)-28=0

Example Question #6 : How To Find X Or Y Intercept

Find the -intercept(s) for the following equation:

Possible Answers:

Correct answer:

Explanation:

To find the  intercepts,  is set equal to . This yields:

And finally

It is important to realize that both  and  must be included because  is also equal to . Finally, these are put into their point forms,  and .

Example Question #12 : X And Y Intercept

What is the largest x-intercept of ?

Possible Answers:

There are no x intercepts for this equation.

Correct answer:

Explanation:

To find the x-intercepts of an equation, you can just set the y value of the equation equal to zero.  Thus you get, for our data:

Now, you can divide everything by  to simplify your equation:

Luckily, this is an easy equation to factor:

Based on this, you know that the two intercepts must be where  and .  Thus, the largest intercept is .

Example Question #13 : X And Y Intercept

What is the sum of the x-intercepts of ?

 

Possible Answers:

Correct answer:

Explanation:

To find the x-intercepts of an equation, you can set its y value equal to zero.  Thus, you get for our equation:

Now, factor out all common factors:

From this, you can further factor:

Thus, the x-intercepts of our equation are ,, and .  The sum of these values is .

Example Question #11 : How To Find X Or Y Intercept

What is the  of the following equation: ?

Possible Answers:

Correct answer:

Explanation:

The y-intercept is the constant at the end of the equation. Thus for our equation the y-intercept is 7

Example Question #13 : How To Find X Or Y Intercept

What is the -intercept of the following linear equation:
?

Give your answer as an ordered pair.

Possible Answers:

Correct answer:

Explanation:

The x-intercept is the value of the linear equation with y = 0 (this means the line will be on the x-axis when y is zero).

Thus we plug 0 in for y and solve for x.

.

Now put it in an ordered pair, remember y = 0:

Example Question #14 : How To Find X Or Y Intercept

What is the  and  intercepts of the linear equation given by:
?

Possible Answers:

Correct answer:

Explanation:

To find the  and  intercept of a linear equation, find the points where  and  are equal to zero.

To do this, plug in zero for either variable and then solve for the other.

 

this yields: 

Example Question #13 : X And Y Intercept

What is the  and  intercepts of the following linear equation:

Possible Answers:

Correct answer:

Explanation:

To find the  and  intercepts of an equation, set each variable to zero (one at a time) and solve for the other variable.

Next, set   to zero:


Now put these two sets of points into two ordered pairs:

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