Precalculus Examples

$(2, - 3)$ , $m = - \frac{1}{2}$

Step 1

Find the value of $b$ using the formula for the equation of a line.

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Step 1.1

Use the formula for the equation of a line to find $b$ .

$y = m x + b$

Step 1.2

Substitute the value of $m$ into the equation.

$y = (- \frac{1}{2}) \cdot x + b$

Step 1.3

Substitute the value of $x$ into the equation.

$y = (- \frac{1}{2}) \cdot (2) + b$

Step 1.4

Substitute the value of $y$ into the equation.

$- 3 = (- \frac{1}{2}) \cdot (2) + b$

Step 1.5

Find the value of $b$ .

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Step 1.5.1

Rewrite the equation as $- \frac{1}{2} \cdot 2 + b = - 3$ .

$- \frac{1}{2} \cdot 2 + b = - 3$

Step 1.5.2

Cancel the common factor of $2$ .

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Step 1.5.2.1

Move the leading negative in $- \frac{1}{2}$ into the numerator.

$\frac{- 1}{2} \cdot 2 + b = - 3$

Step 1.5.2.2

Cancel the common factor.

$\frac{- 1}{2} \cdot 2 + b = - 3$

Step 1.5.2.3

Rewrite the expression.

$- 1 + b = - 3$

Step 1.5.3

Move all terms not containing $b$ to the right side of the equation.

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Step 1.5.3.1

Add $1$ to both sides of the equation.

$b = - 3 + 1$

Step 1.5.3.2

Add $- 3$ and $1$ .

$b = - 2$

Step 2

Now that the values of $m$ (slope) and $b$ (y-intercept) are known, substitute them into $y = m x + b$ to find the equation of the line.

$y = - \frac{1}{2} x - 2$

Step 3