SAT II Math II : X-intercept and y-intercept

Study concepts, example questions & explanations for SAT II Math II

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Example Questions

Example Question #244 : Sat Subject Test In Math Ii

Find the y-intercept of the following equation:

\displaystyle 3x-y=12

Possible Answers:

\displaystyle y=12

\displaystyle x=-12

\displaystyle x=12

\displaystyle y=-12

Correct answer:

\displaystyle y=-12

Explanation:

In order to find the y-intercept, set x=0 then solve for y. For this equation that looks as follows:

\displaystyle 3x-y=12\rightarrow 0-y=12

Divide both sides by -1 to get y by itself:

\displaystyle \frac{-1y}{-1}=\frac{12}{-1}

This gives a final answer of y=-12

Example Question #245 : Sat Subject Test In Math Ii

Find the y-intercept of the following equation:

\displaystyle y=6x+2

Possible Answers:

\displaystyle x=6

\displaystyle y=3

\displaystyle y=2

\displaystyle x=2

Correct answer:

\displaystyle y=2

Explanation:

In order to find the y-intercept, set x=0 then solve for y. For this equation that looks as follows:

\displaystyle y=6x+2\rightarrow y=0+2

This gives a final answer of y=2

Example Question #34 : Functions And Graphs

What is the y-intercept of the following equation?  \displaystyle 2y-2 = 2x+2

Possible Answers:

\displaystyle 2

\displaystyle 0

\displaystyle \textup{The equation is not linear.}

\displaystyle 1

\displaystyle -\frac{1}{2}

Correct answer:

\displaystyle 2

Explanation:

Rewrite the equation in slope-intercept form:

\displaystyle y=mx+b

Our objective is to determine the value of \displaystyle b, which represents the y-intercept.

Add two on both sides.

\displaystyle 2y-2 +(2)= 2x+2+(2)

\displaystyle 2y= 2x+4

Divide by 2 on both sides.

\displaystyle \frac{2y}{2}=\frac{ 2x+4}{2}

\displaystyle y= x+2

The value of \displaystyle b =2.

Example Question #34 : Functions And Graphs

What is the y-intercept of the following?  \displaystyle y=2(2x-3)^2

Possible Answers:

\displaystyle 6

\displaystyle -18

\displaystyle 36

\displaystyle -9

\displaystyle 18

Correct answer:

\displaystyle 18

Explanation:

The y-intercept is the value of \displaystyle y when \displaystyle x=0.

Substitute the value of \displaystyle x=0 into the given equation.

\displaystyle y=2(2(0)-3)^2 = 2(0-3)^2 = 2(-3)^2 = 2(9)

The answer is:  \displaystyle 18

Example Question #34 : Functions And Graphs

What is the x-intercept of the equation \displaystyle y= 3x-2?

Possible Answers:

\displaystyle -\frac{3}{2}

\displaystyle -2

\displaystyle 2

\displaystyle \frac{3}{2}

\displaystyle \frac{2}{3}

Correct answer:

\displaystyle \frac{2}{3}

Explanation:

The x-intercept is the value of x when \displaystyle y=0.

\displaystyle 0= 3x-2

Add two on both sides, and then divide both sides by three.

\displaystyle 0+2= 3x-2+2

\displaystyle 2=3x

The answer is:  \displaystyle \frac{2}{3}

Example Question #35 : Functions And Graphs

Define \displaystyle h(x)=6- \log _{3}\left ( x-7 \right ).

Give the \displaystyle y-coordinate of the \displaystyle y-intercept of the graph of \displaystyle h (nearest hundredth).

Possible Answers:

The graph of \displaystyle h has no \displaystyle y-intercept.

\displaystyle 7.77

\displaystyle 4.23

\displaystyle 6.56

\displaystyle 5.44

Correct answer:

The graph of \displaystyle h has no \displaystyle y-intercept.

Explanation:

Evaluate \displaystyle h(0):

\displaystyle h(x)=6- \log _{3}\left ( x-7 \right )

\displaystyle h(0)=6- \log _{3}\left ( 0-7 \right )

\displaystyle h(0)=6- \log _{3}\left ( -7 \right )

A negative number cannot have a logarithm, so \displaystyle h(0) is an undefined expression. Therefore, the graph of \displaystyle h has no \displaystyle y-intercept.

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