Question

ion 8. The graph of a linear function passes through (-8,9) and (3, -13). Which is the equation for the function? A y = ext 13 5 5 B. y = -2x - 7 C. y = 4x + *** } D. y = -2x - 25

Answer 1

Step 1

We find the gradient(slope) of the graph using the formula below:

$\begin{gathered} m=\frac{y_2-y_1}{x_2-x_1} \\ =\frac{-13-9}{3-(-8)} \\ =\frac{-22}{11} \\ =-2 \\ \end{gathered}$

Step 2

We find the equation of the line using the formula below

$\begin{gathered} m=\frac{y-y_1}{x-x_1} \\ m=\frac{y-9}{x-(-8)} \\ m=\frac{y-9}{x+8} \\ \text{Cross multiply} \\ -2=\frac{y-9}{x+8} \\ -2(x+8)=y-9 \\ -2x-16=y-9 \\ y=-2x-16+9 \\ y=-2x-7 \\ \end{gathered}$

Therefore the answer is option B