Intermediate Geometry : x and y Intercept

Study concepts, example questions & explanations for Intermediate Geometry

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Example Questions

Example Question #71 : How To Find X Or Y Intercept

What is the y-intercept of the line that has the equation \(\displaystyle y-8=\frac{1}{10}(x+200)\)?

Possible Answers:

\(\displaystyle (0, 20)\)

\(\displaystyle (0, 18)\)

\(\displaystyle (0, 28)\)

\(\displaystyle (0, 32)\)

Correct answer:

\(\displaystyle (0, 28)\)

Explanation:

You should recognize that the given equation is in the point-slope form.

In order to find the y-intercept, rearrange the equation into slope-intercept form, \(\displaystyle y=mx+b\).

\(\displaystyle y-8=\frac{1}{10}(x+200)\)

\(\displaystyle y-8=\frac{1}{10}x+20\)

\(\displaystyle y=\frac{1}{10}x+28\)

Since, \(\displaystyle b=28\), the y-intercept must be located at \(\displaystyle (0,28)\).

Example Question #72 : How To Find X Or Y Intercept

What is the y-intercept of the line that has the equation \(\displaystyle y-7=-2(x-10)\)?

Possible Answers:

\(\displaystyle (0, 24)\)

\(\displaystyle (0, 18)\)

\(\displaystyle (0, 27)\)

\(\displaystyle (0, -17)\)

Correct answer:

\(\displaystyle (0, 27)\)

Explanation:

You should recognize that the given equation is in the point-slope form.

In order to find the y-intercept, rearrange the equation into slope-intercept form, \(\displaystyle y=mx+b\).

\(\displaystyle y-7=-2(x-10)\)

\(\displaystyle y-7=-2x+20\)

\(\displaystyle y=-2x+27\)

Since, \(\displaystyle b=27\), the y-intercept must be located at \(\displaystyle (0,27)\).

Example Question #71 : X And Y Intercept

Find the y-intercept of the line that has the equation \(\displaystyle y+15=-7(x-2)\).

Possible Answers:

\(\displaystyle (0, -13)\)

\(\displaystyle (0, -1)\)

\(\displaystyle (0, -3)\)

\(\displaystyle (0, -19)\)

Correct answer:

\(\displaystyle (0, -1)\)

Explanation:

You should recognize that the given equation is in the point-slope form.

In order to find the y-intercept, rearrange the equation into slope-intercept form, \(\displaystyle y=mx+b\).

\(\displaystyle y+15=-7(x-2)\)

\(\displaystyle y+15=-7x+14\)

\(\displaystyle y=-7x-1\)

Since, \(\displaystyle b=-1\), the y-intercept must be located at \(\displaystyle (0,-1)\).

Example Question #74 : How To Find X Or Y Intercept

What is the y-intercept of a line that has the equation \(\displaystyle y-24=-8(x+1)\)?

Possible Answers:

\(\displaystyle (0, 16)\)

\(\displaystyle (0, 24)\)

\(\displaystyle (0, 10)\)

\(\displaystyle (0, 8)\)

Correct answer:

\(\displaystyle (0, 16)\)

Explanation:

You should recognize that the given equation is in the point-slope form.

In order to find the y-intercept, rearrange the equation into slope-intercept form, \(\displaystyle y=mx+b\).

\(\displaystyle y-24=-8(x+1)\)

\(\displaystyle y-24=-8x-8\)

\(\displaystyle y=-8x+16\)

Since, \(\displaystyle b=16\), the y-intercept must be located at \(\displaystyle (0,16)\).

Example Question #75 : How To Find X Or Y Intercept

What is the y-intercept of a line that has the equation \(\displaystyle y+29=-\frac{1}{4}(x+36)\)?

Possible Answers:

\(\displaystyle (0, 2)\)

\(\displaystyle (0,-38)\)

\(\displaystyle (0, -18)\)

\(\displaystyle (0, -29)\)

Correct answer:

\(\displaystyle (0,-38)\)

Explanation:

You should recognize that the given equation is in the point-slope form.

In order to find the y-intercept, rearrange the equation into slope-intercept form, \(\displaystyle y=mx+b\).

\(\displaystyle y+29=-\frac{1}{4}(x+36)\)

\(\displaystyle y+29=-\frac{1}{4}x-9\)

\(\displaystyle y=-\frac{1}{4}x-38\)

Since, \(\displaystyle b=-38\), the y-intercept must be located at \(\displaystyle (0,-38)\).

Example Question #76 : How To Find X Or Y Intercept

What is the y-intercept of the line with the equation? 

\(\displaystyle y-10=-20(x+\frac{1}{4})\)

Possible Answers:

\(\displaystyle (0, 5)\)

\(\displaystyle (0, 21)\)

\(\displaystyle (0, 18)\)

\(\displaystyle (0, 24)\)

Correct answer:

\(\displaystyle (0, 5)\)

Explanation:

You should recognize that the given equation is in the point-slope form.

In order to find the y-intercept, rearrange the equation into slope-intercept form, \(\displaystyle y=mx+b\).

\(\displaystyle y-10=-20(x+\frac{1}{4})\)

\(\displaystyle y-10=-20x-5\)

\(\displaystyle y=-20x+5\)

Since, \(\displaystyle b=5\), the y-intercept must be located at \(\displaystyle (0,5)\).

Example Question #77 : How To Find X Or Y Intercept

True or false: The lines of the equations 

\(\displaystyle 2x+y = 12\)

and

\(\displaystyle x+2y = 12\)

have the same \(\displaystyle y\)-intercept.

Possible Answers:

True

False

Correct answer:

False

Explanation:

The \(\displaystyle y\)-intercept of a line is the point at which it intersects the \(\displaystyle y\)-axis; its \(\displaystyle x\)-coordinate at this point is 0, so its \(\displaystyle y\)-coordinate can be found by substituting 0 for \(\displaystyle x\) in the equation and solving for \(\displaystyle y\). Do this with both equations:

\(\displaystyle 2x+y = 12\)

\(\displaystyle 2 \cdot 0 +y = 12\)

\(\displaystyle 0+ y = 12\)

\(\displaystyle y = 12\)

The \(\displaystyle y\)-intercept of the line is at \(\displaystyle (0, 12)\).

 

\(\displaystyle x+2y = 12\)

\(\displaystyle 0+2y = 12\)

\(\displaystyle 2y = 12\)

\(\displaystyle \frac{2y }{2}= \frac{12}{2}\)

\(\displaystyle y = 6\)

The \(\displaystyle y\)-intercept of the line is at \(\displaystyle (0, 6)\).

The two lines have different \(\displaystyle y\)-intercepts.

Example Question #78 : How To Find X Or Y Intercept

True or false: the lines of the equations

\(\displaystyle y = 6\)

and

\(\displaystyle x+ y = 6\)

have the same \(\displaystyle y\)-intercept.

Possible Answers:

True

False

Correct answer:

True

Explanation:

The \(\displaystyle y\)-intercept of a line is the point at which it intersects the \(\displaystyle y\)-axis; its \(\displaystyle x\)-coordinate at this point is 0.

The \(\displaystyle y\)-coordinate of the line of the equation

\(\displaystyle x+ y = 6\)

can be found by substituting 0 for \(\displaystyle x\) in the equation and solving for \(\displaystyle y\):

\(\displaystyle 0+ y = 6\)

\(\displaystyle y=6\)

The \(\displaystyle y\)-intercept of this line is at \(\displaystyle (0,6)\).

The line with equation \(\displaystyle y = b\) is a horizontal line with its \(\displaystyle y\)-intercept at \(\displaystyle (0,b)\), so the \(\displaystyle y\)-intercept line of the equation \(\displaystyle y=6\) has its \(\displaystyle y\)-intercept at \(\displaystyle (0,6)\) as well.

Both lines indeed have the same \(\displaystyle y\)-intercept.

Example Question #72 : X And Y Intercept

True or false:

The lines of the equations

\(\displaystyle y = \frac{2}{5}x+ 117\)

and

\(\displaystyle y = - \frac{5}{2}x+ 117\)

have the same \(\displaystyle y\)-intercept.

Possible Answers:

False

True

Correct answer:

True

Explanation:

Both equations are given in the slope-intercept form \(\displaystyle y = mx+b\), in which the stand-alone constant \(\displaystyle b\) is the \(\displaystyle y\)-coordinate of the \(\displaystyle y\)-intercept. In both equations, this value is 117, so \(\displaystyle (0, 117 )\) is the \(\displaystyle y\)-intercept of both equations.

Example Question #1582 : Intermediate Geometry

Find the y-intercept of a line that has a slope of \(\displaystyle 5\) and passes through the point \(\displaystyle (12, 4)\).

Possible Answers:

\(\displaystyle (0, -14)\)

\(\displaystyle (0, -56)\)

\(\displaystyle (0, 55)\)

\(\displaystyle (0,5)\)

Correct answer:

\(\displaystyle (0, -56)\)

Explanation:

Recall the point-slope form of the equation of a line that has a slope of \(\displaystyle m\) and passes through the point \(\displaystyle (x_1, y_1)\):

\(\displaystyle y-y_1=m(x-x_1)\)

Plug in the given point and the given slope.

\(\displaystyle y-4=5(x-12)\)

Rearrange the equation into slope-intercept form.

\(\displaystyle y-4=5x-60\)

\(\displaystyle y=5x-56\)

The y-intercept for this line is \(\displaystyle (0, -56)\).

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