You have learned that each line in the coordinate plane has both an \( x \)- and a \( y \)-intercept and that a single line can be represented by many different point-slope equations. The point-slope form of a line is \( y - y_{1} = m(x - x_{1}) \). You can follow a series of steps to rewrite each point-slope equation in slope-intercept form, \( y = mx + b \). It's your turn to practice this skill!
How well can you convert the equation of a line from point-slope form to slope-intercept form? Use the activity below to practice. Convert each equation from point-slope form to slope-intercept form. Then, name the \( x \)- and \( y \)-intercepts of each equation, and check your answer.
Rewrite the equation \( y - ( - 7) = - 2(x - 2) \) in slope-intercept form. Give the coordinates of both its \( x \)- and \( y \)-intercepts.
\( y = - 2x - 3 \)
\( x \)-intercept: \( \left( - \frac{3}{2},0 \right) \)
\( y \)-intercept: \( \left( 0, - 3 \right) \)
If you need help arriving at this answer, click the Solution button.
Step 1: Simplify any double negatives. |
There is a double negative on the left-hand side of the equation. \( y \ \require{color}\colorbox{yellow}{$ - \left( - 7 \right) $} = - 2\left( x - 2 \right) \) \( y \ \require{color}\colorbox{yellow}{$ + 7 $} = - 2(x - 2) \) |
Step 2: Distribute on the right-hand side of the equation. |
\( y + 7 = - 2\left( x - 2 \right) \) \( y + 7 = - 2x + 4 \) |
Step 3: Collect the like terms. |
\( y + 7 {\color{#A80000}{\ - 7}} = - 2x + 4 {\color{#A80000}{\ - 7}} \) \( y = - 2x - 3 \) |
Step 4: Read the location of the \( y \)-intercept from the equation. |
\( \left( 0, - 3 \right) \) |
Step 5: Solve for the location of the \( x \)-intercept. |
Substitute \( y = 0 \) into the slope-intercept form of the equation. \( (0) = - 2x - 3 \) \( 0 {\color{#A80000}{\ +\ 3}} = - 2x - 3 {\color{#A80000}{\ +\ 3}} \) \( 3 = - 2x \) \( - \frac{3}{2} = x \) The \( x \)-intercept is \( \left( - \frac{3}{2},0 \right) \). |
Rania and Portia are working on the design plans for the drainage systems of the pools in the city of Geocove's waterpark. The maximum rate at which Pool 1 can be drained is represented by the equation \( y - 1800 = - 300(x - 0) \).
Rewrite this equation in slope-intercept form and give the coordinates of both its \( x \)- and \( y \)-intercepts.
\( y = - 300x + 1800 \)
\( x \)-intercept: \( \left( 6,0 \right) \)
\( y \)-intercept: \( \left( 0,\ 1800 \right) \)
If you need help arriving at this answer, click the Solution button.
Step 1: Simplify any double negatives. |
This equation does not contain any double negatives. |
Step 2: Distribute on the right-hand side of the equation. |
\( y - 1800 = - 300(x - 0) \) \( y - 1800 = - 300x \) |
Step 3: Collect the like terms. |
\( y - 1800 {\color{#A80000}{\ +\ 1800}} = - 300x {\color{#A80000}{\ +\ 1800}} \) \( y = - 300x + 1800 \) |
Step 4: Read the location of the \( y \)-intercept from the equation. |
\( \left( 0,\ 1800 \right) \) |
Step 5: Solve for the location of the \( x \)-intercept. |
Substitute \( y = 0 \) into the slope-intercept form of the equation. \( \left( 0 \right) = - 300x + 1800 \) \( 0 {\color{#A80000}{\ - 1800}} = - 300x + 1800 {\color{#A80000}{\ - 1800}} \) \( - \frac{1800}{ {\color{#A80000}{- 300}}} = - \frac{300x}{ {\color{#A80000}{- 300}}} \) \( 6 = x \) The \( x \)-intercept is \( \left( 6,0 \right) \). |
Rewrite the equation \( y - 10 = \frac{1}{4}(x - 16) \) in slope-intercept form. Give the coordinates of both its \( x \)- and \( y \)-intercepts.
\( y = \frac{1}{4}x + 6 \)
\( x \)-intercept: \( \left( - 24,0 \right) \)
\( y \)-intercept: \( \left( 0,\ 6 \right) \)
If you need help arriving at this answer, click the Solution button.
Step 1: Simplify any double negatives. |
This equation does not contain any double negatives. |
Step 2: Distribute on the right-hand side of the equation. |
\( y - 10 = \frac{1}{4}\left( x - 16 \right) \) \( y - 10 = \frac{1}{4}x - 4 \) |
Step 3: Collect the like terms. |
\( y - 10 {\color{#A80000}{\ +\ 10}} = \frac{1}{4}x - 4 {\color{#A80000}{\ +\ 10}} \) \( y = \frac{1}{4}x + 6 \) |
Step 4: Read the location of the \( y \)-intercept from the equation. |
\( \left( 0,\ 6 \right) \) |
Step 5: Solve for the location of the \( x \)-intercept. |
Substitute \( y = 0 \) into the slope-intercept form of the equation. \( (0) = \frac{1}{4}x + 6 \) \( - 6 = \frac{1}{4}x \) \( - 24 = x \) The \( x \)-intercept is \( \left( - 24,0 \right) \). |
Rania and Portia are working on the design plans for the drainage systems of the pools in Geocove's waterpark. The maximum rate at which Pool 2 can be drained is represented by the equation \( y - ( - 3600) = - 600(x - 13) \).
Rewrite this equation in slope-intercept form and give the coordinates of both its \( x \)- and \( y \)-intercepts.
\( y = - 600x + 4200 \)
\( x \)-intercept: \( \left( 7,0 \right) \)
\( y \)-intercept: \( \left( 0,\ 4200 \right) \)
If you need help arriving at this answer, click the Solution button.
Step 1: Simplify any double negatives. |
\( y - ( - 3600) = - 600(x - 13) \) \( y + 3600 = - 600(x - 13) \) |
Step 2: Distribute on the right-hand side of the equation. |
\( y + 3600 = - 600\left( x - 13 \right) \) \( y + 3600 = - 600x + 7800 \) |
Step 3: Collect the like terms. |
\( y + 3600 {\color{#A80000}{\ - 3600}} = - 600x + 7800 {\color{#A80000}{\ - 3600}} \) \( y = - 600x + 4200 \) |
Step 4: Read the location of the \( y \)-intercept from the equation. |
\( \left( 0,\ 4200 \right) \) |
Step 5: Solve for the location of the \( x \)-intercept. |
Substitute \( y = 0 \) into the slope-intercept form of the equation. \( \left( 0 \right) = - 600x + 4200 \) \( - 4200 = - 600x \) \( 7 = x \) The \( x \)-intercept is \( \left( 7,0 \right) \). |
Rania and Portia are working on the design plans for the drainage systems of the pools in Geocove's waterpark. The maximum rate at which Pool 3 can be drained is represented by the equation \( y - 7200 = - 900(x - 3) \).
Rewrite this equation in slope-intercept form and give the coordinates of both its \( x \)- and \( y \)-intercepts.
\( y = - 900x + 9900 \)
\( x \)-intercept: \( \left( 11,0 \right) \)
\( y \)-intercept: \( \left( 0,\ 9900 \right) \)
If you need help arriving at this answer, click the Solution button.
Step 1: Simplify any double negatives. |
This equation does not contain any double negatives. |
Step 2: Distribute on the right-hand side of the equation. |
\( y - 7200 = - 900\left( x - 3 \right) \) \( y - 7200 = - 900x + 2700 \) |
Step 3: Collect the like terms. |
\( y - 7200 = - 900x + 2700 \) \( y = - 900x + 9900 \) |
Step 4: Read the location of the \( y \)-intercept from the equation. |
\( \left( 0,\ 9900 \right) \) |
Step 5: Solve for the location of the \( x \)-intercept. |
Substitute \( y = 0 \) into the slope-intercept form of the equation. \( (0) = - 900x + 9900 \) \( - 9900 = - 900x \) \( 11 = x \) The \( x \)-intercept is \( \left( 11,0 \right) \). |