Find the Equation Using Slope-Intercept Form m=-2 and (2,4)

$m = - 2$ and $(2, 4)$

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

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

$y = m x + b$

Substitute the value of $m$ into the equation.

$y = (- 2) \cdot x + b$

Substitute the value of $x$ into the equation.

$y = (- 2) \cdot (2) + b$

Substitute the value of $y$ into the equation.

$4 = (- 2) \cdot (2) + b$

Find the value of $b$ .

Rewrite the equation as $(- 2) \cdot (2) + b = 4$ .

$(- 2) \cdot (2) + b = 4$

Multiply $- 2$ by $2$ .

$- 4 + b = 4$

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

Add $4$ to both sides of the equation.

$b = 4 + 4$

Add $4$ and $4$ .

$b = 8$

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.

$y = - 2 x + 8$