Question

If $f(x)=2-2x^2,$ find $\frac{f(3,8)-f(4)}{3.8-4}$,

• A. 1.56
• B. 156
• C. 15.6
• D. 0.156

Answer 1

Answer: (C)

We have, $f\left(x\right)=2x^2$
$\therefore \frac{f\left(3.8\right)-f\left(4\right)}{3.8-4}=\frac{2{\left(3.8\right)}^2-2{\left(4\right)}^2}{3.8-4}$
$=\frac{2\left[{\left(3.8\right)}^2-{\left(4\right)}^2\right]}{3.8-4}$
$=\frac{2\left(3.8-4\right)\left(3.8+4\right)}{3.8}=2\left(7.8\right)=15.6$