(1+h)^3 please help if you know it?

You mean its expansion? Simple multiplication reveals it:

1 + 3h + 3h^2 + h^3

(1 + h)^3
= (1 + h)(1 + h)(1 + h)
= (1*1 + h*1 + 1*h + h*h)(1 + h)
= (1 + h + h + h^2)(1 + h)
= (1 + 2h + h^2)(1 + h)
= 1*1 + 2h*1 + h^2*1 + 1*h + 2h*h + h^2*h
= 1 + 2h + h^2 + h + 2h^2 + h^3
= 1 + 2h + h + h^2 + 2h^2 + h^3
= 1 + 3h + 3h^2 + h^3

(1 + h) ( 1 + 2 h + h ² )

1 + 2 h + h ² + h + 2 h ² + h ³

h ³ + 3 h ² + 3 h + 1

there is a short cut for the expansion of binomials:

1 (a+b)^0
1 1 (a+b)^1
1 2 1 (a+b)^2 = a^2 + 2ab + b^2
1 3 3 1 (a+b)^3= a^3 + 3a^2b + 3ab^2 + b^3
1 4 6 4 1 (a+b)^4= a^4 + 4a^3b + 6a^2b^2 + 4ab^3 + b^4

1 + 3h + 3h^2 + h^3

Well if this is from calculus usually when h is used ,,, its value tends to 0....
In that case h^2 or h^3 become so very small that they can be neglected.....

If not then proceed as multiplication.......