Precalculus Examples

$3 x - 5 y = 15$

Step 1

Solve for $y$ .

Tap for more steps...

Step 1.1

Subtract $3 x$ from both sides of the equation.

$- 5 y = 15 - 3 x$

Step 1.2

Divide each term in $- 5 y = 15 - 3 x$ by $- 5$ and simplify.

Tap for more steps...

Step 1.2.1

Divide each term in $- 5 y = 15 - 3 x$ by $- 5$ .

$\frac{- 5 y}{- 5} = \frac{15}{- 5} + \frac{- 3 x}{- 5}$

Step 1.2.2

Simplify the left side.

Tap for more steps...

Step 1.2.2.1

Cancel the common factor of $- 5$ .

Tap for more steps...

Step 1.2.2.1.1

Cancel the common factor.

$\frac{- 5 y}{- 5} = \frac{15}{- 5} + \frac{- 3 x}{- 5}$

Step 1.2.2.1.2

Divide $y$ by $1$ .

$y = \frac{15}{- 5} + \frac{- 3 x}{- 5}$

Step 1.2.3

Simplify the right side.

Tap for more steps...

Step 1.2.3.1

Simplify each term.

Tap for more steps...

Step 1.2.3.1.1

Divide $15$ by $- 5$ .

$y = - 3 + \frac{- 3 x}{- 5}$

Step 1.2.3.1.2

Dividing two negative values results in a positive value.

$y = - 3 + \frac{3 x}{5}$

Step 2

Rewrite in slope-intercept form.

Tap for more steps...

Step 2.1

The slope-intercept form is $y = m x + b$ , where $m$ is the slope and $b$ is the y-intercept.

$y = m x + b$

Step 2.2

Reorder $- 3$ and $\frac{3 x}{5}$ .

$y = \frac{3 x}{5} - 3$

Step 2.3

Reorder terms.

$y = \frac{3}{5} x - 3$

Step 3

Use the slope-intercept form to find the slope and y-intercept.

Tap for more steps...

Step 3.1

Find the values of $m$ and $b$ using the form $y = m x + b$ .

$m = \frac{3}{5}$

$b = - 3$

Step 3.2

The slope of the line is the value of $m$ , and the y-intercept is the value of $b$ .

Slope: $\frac{3}{5}$

y-intercept: $(0, - 3)$

Slope: $\frac{3}{5}$

y-intercept: $(0, - 3)$

Step 4

Any line can be graphed using two points. Select two $x$ values, and plug them into the equation to find the corresponding $y$ values.

Tap for more steps...

Step 4.1

Write in $y = m x + b$ form.

Tap for more steps...

Step 4.1.1

Reorder $- 3$ and $\frac{3 x}{5}$ .

$y = \frac{3 x}{5} - 3$

Step 4.1.2

Reorder terms.

$y = \frac{3}{5} x - 3$

Step 4.2

Create a table of the $x$ and $y$ values.

$\begin{array}{c} x & y \\ 0 & - 3 \\ 5 & 0 \end{array}$

Step 5

Graph the line using the slope and the y-intercept, or the points.

Slope: $\frac{3}{5}$

y-intercept: $(0, - 3)$

$\begin{array}{c} x & y \\ 0 & - 3 \\ 5 & 0 \end{array}$

Step 6