PSAT Math : How to find x or y intercept

Study concepts, example questions & explanations for PSAT Math

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Example Questions

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Example Question #1 : How To Find X Or Y Intercept

Determine the y-intercept of the following line:

\dpi{100} \small 3x+6y=9

Possible Answers:

\dpi{100} \small 6

\dpi{100} \small \frac{1}{3}

\dpi{100} \small 9

\dpi{100} \small 3

\dpi{100} \small 1.5

Correct answer:

\dpi{100} \small 1.5

Explanation:

The y-intercept occurs when \dpi{100} \small x=0

\dpi{100} \small 3x+6y=9

\dpi{100} \small 3(0)+6y=9

\dpi{100} \small 0+6y=9

\dpi{100} \small y = \frac{9}{6}=1.5

Example Question #2 : How To Find X Or Y Intercept

At what point does the graph 3y-2x=31 cross the -axis?

Possible Answers:

Correct answer:

Explanation:

The graph crosses the -axis where x=0. So plugging in and solving yields \frac{31}{3}

Example Question #21 : Arcs And Intercept

Find the x-intercepts of  25x^{2}+4y^{2} = 9.

Possible Answers:

5

2

\frac{3}{5}

\pm \frac{3}{5}

\pm 5

Correct answer:

\pm \frac{3}{5}

Explanation:

To find the x-intercepts, plug y=0 into the equation and solve for x.

25x^{2} + 4\cdot 0^{2} = 9

25x^{2} = 9

x^{2} = \frac{9}{25}

x = \pm \frac{3}{5}

Don't forget that there are two solutions, both negative and positive!

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

A line with the exquation y=x^2+3x+c passes through the point .  What is the -intercept?

Possible Answers:

Correct answer:

Explanation:

By plugging in the coordinate, we can figure out that .  The -Intercept is when , plugging in 0 for gives us .

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

What are the -intercept(s) of the following line:

Possible Answers:

Correct answer:

Explanation:

We can factor and set  equal to zero to determine the -intercepts.

satisfies this equation.

 

Therefore our -intercepts are  and .

Example Question #592 : Sat Mathematics

Which of the following lines does not intersect the line ?

Possible Answers:

Correct answer:

Explanation:

Parallel lines never intersect, so you are looking for a line that has the same slope as the one given. The slope of the given line is –4, and the slope of the line in y = –4x + 5 is –4 as well. Since these two lines have equal slopes, they will run parallel and can never intersect.

Example Question #22 : How To Find X Or Y Intercept

Where does the line given by y=3(x-4)-9 intercept the -axis?

Possible Answers:

Correct answer:

Explanation:

First, put in slope-intercept form. 

y=3x-21

To find the -intercept, set  and solve for .

Example Question #11 : X And Y Intercept

Find the y-intercept of .

Possible Answers:

12

3

14

5

7

Correct answer:

7

Explanation:

To find the y-intercept, set x equal to zero and solve for y.

This gives y = 3(0)2 + 2(0) +7 = 7.

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

The slope of a line is m=\frac{4}{3}. The line passes through (2,7). What is the x-intercept?

Possible Answers:

(0,9\frac{2}{3})

(0,4.3)

(4\frac{1}{3},0)

None of the available answers

Correct answer:

Explanation:

The equation for a line is:

y=mx+b, or in this case

y=\frac{4}{3}x+b

We can solve for b by plugging in the values given

7=\frac{4}{3}\times 2+b

7=2\frac{2}{3}+b

b=7-2\frac{2}{3}=4\frac{1}{3}

Our line is now

y=\frac{4}{3}x+4\frac{1}{3}

Our x-intercept occurs when \dpi{100} y=0, so plugging in and solving for \dpi{100} x:

\dpi{100} 0=\frac{4}{3}x+4\frac{1}{3}

\dpi{100} -\frac{13}{3}=\frac{4}{3}x

\dpi{100} x=-\frac{13}{4}

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