Question

Compute the difference​ quotient, StartFraction f (x plus h )minus f (x )Over h EndFraction f(x+h)−f(x) h​, for the function f (x )equals 3 x squaredf(x)=3x2​, and simplify.

Answer 1

Answer:

The difference quotient for $f(x)=3x^2$ is $3 h + 6 x$.

Step-by-step explanation:

The difference quotient is a formula that computes the slope of the secant line through two points on the graph of f. These are the points with x-coordinates x and x + h. The difference quotient is used in the definition the derivative and it is given by

$\frac{f(x+h)-f(x)}{h}$

So, for the function $f(x)=3x^2$ the difference quotient is:

To find $f(x+h)$, plug $x+h$ instead of $x$

$f\left(x+h\right)=3 \left(h + x\right)^{2}$

Finally,

$\frac{f\left(x+h\right)-f\left(x\right)}{h}=\frac{\left(3 \left(h + x\right)^{2}\right)-\left(3 x^{2}\right)}{h}$

$\frac{3\left(\left(h+x\right)^2-x^2\right)}{h} \\\\\frac{3(h^2+2hx+x^2-x^2)}{h} \\\\\frac{3h\left(h+2x\right)}{h}\\\\3h+6x$

The difference quotient for $f(x)=3x^2$ is $3 h + 6 x$.