[tex]\bf slope = m = \cfrac{rise}{run} \implies \cfrac{ f(x_2) - f(x_1)}{ x_2 - x_1}\impliedby \begin{array}{llll} average~rate\\ of~change \end{array}\\\\[-0.35em] \rule{31em}{0.25pt}\\\\ h(x)= 2x^2\qquad 2\leqslant x \leqslant 4 \qquad \begin{cases} x_1=2\\ x_2=4 \end{cases}\implies \cfrac{h(4)-h(2)}{4-2} \\\\\\ \cfrac{2(4)^2~~-~~2(2)^2}{2}\implies \cfrac{32-8}{2}\implies \cfrac{24}{2}\implies 12[/tex]