Question

Ƒ (x) = x² − 2x – 4.

What is the average rate of change for the quadratic function from x = − 1 to x =4

Answer 1

`\begin{array}{llll} f(x)~from\\\\ x_1 ~~ to ~~ x_2 \end{array}~\hfill slope = m \implies \cfrac{ \stackrel{rise}{f(x_2) - f(x_1)}}{ \underset{run}{x_2 - x_1}}\impliedby \begin{array}{llll} average~rate\\ of~change \end{array} \\\\[-0.35em] ~\dotfill\\\\ f(x)= x^2-2x-4 \qquad \begin{cases} x_1=-1\\ x_2=4 \end{cases}\implies \cfrac{f(4)-f(-1)}{4 - (-1)} \\\\\\ \cfrac{[(4)^2-2(4)-4]~~ - ~~[(-1)^2-2(-1)-4]}{4+1}\implies \cfrac{4~~ - ~~(-1)}{5} \\\\\\ \cfrac{4+1}{5}\implies \cfrac{5}{5}\implies 1`