Can some help me with this problem with limits

Ok, so I need help with finding the answer to this...

evaluate the limit, if it exist

((h+x)^3-x^3)/h limit h-->0

You are being introduced to Calculus. First expand the cubic

(x + h)^3 = x^3 + 3x^2*h + 3x*h^2 + h^3

Now realize that you are going to take x^3 from this

(x + h)^3 - x^3 = 3x^2h + 3xh^2 + h^3

Now divide by h
h(3x^2 + 3xh + h^2)
=============
h

The h's will cancel out.
What you are left with is
3x^2 + 3xh + h^2

Use this to get a limit
limit (3x^2 + 3xh + h^2)
h-->0
leaves 3x^2

Answer 3x^2

A) Don't start a statement with "OK, so..."

B) ((h+x)^3-x^3)/h = (x^3 +3x^2h+3xh^2+h^3 -x^3)/h = (3x^2h+3xh^2+h^3)/h = 3x^2+3xh+h^2

limit h-->0 ((h+x)^3-x^3)/h = limit h-->0 3x^2+3xh+h^2 = 3x^2

Remember that
a³ - b³ = (a - b)(a² + ab + b²)

Apply this rule, where
a = h + x
b = x

[(h + x) - x][(h + x)² + (h + x)x + x²]/h
h[(h + x)² + (h + x)x + x²]/h
[(h + x)² + (h + x)x + x²]

lim_h→0 [(h + x)² + (h + x)x + x²] = 3x²

This is also the differentiation of x^3, which is 3x^2