$\"\"$

The function $\"f\\left$ .

Find $\"\"$ $\"f\\left$ .

Substitute $\"x=a\"$ in $\"f\\left$ .

$\"f\\left$ .

$\"\"$

Find $\"f\\left$ .

Substitute $\"x=a+h\"$ in $\"f\\left$ .

$\"f\\left$

Apply the fomula: $\"(a+b)^3=a^3+b^3+3a^2b+3ab^2\"$ .

Here $\"a=a,$ .

$\"f\\left$ .

$\"\"$

Find $\"\\frac{f\\left$ .

Substitute the values of $\"f\\left$ and $\"f\\left$ .

$\"\\frac{f\\left$

$\"=\\frac{a^3+h^3+3a^2h+3ah^2+9-a^3-9}{h}\"$

$\"=\\frac{h(h^2+3a^2+3ah)}{h}\"$

$\"\\frac{f(a+h)-f(a)}{h}=h^2+3a^2+3ah\"$ .

$\"\"$

$\"f\\left$ .

$\"f\\left$ .

$\"\\frac{f(a+h)-f(a)}{h}=h^2+3a^2+3ah\"$ .