$\"\"$

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 formula: $\"(a+b)^2=a^2+b^2+2ab\"$ .

Here $\"a=a,$ .

$\"f\\left$

$\"f\\left$ .

$\"\"$

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

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

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

$\"=\\frac{h(5h+10a)}{h}\"$

$\"\\frac{f(a+h)-f(a)}{h}=5h+10a\"$ .

$\"\"$

$\"f\\left$ .

$\"f\\left$ .

$\"\\frac{f(a+h)-f(a)}{h}=5h+10a\"$ .