Find the mistake in the below maths equations

A = 2
A(A-1) = 2(A-1)
A2-A = 2A-2
A2-2A = A-2
A(A-2) = A-2
A = 1

You need to arrange three 7 and mathematical symbols to form number 1?

Can you think of any three-dimensional shape that comprises of exactly two surfaces?

Get total of 120 by using five zeros 0,0,0,0,0 and any one mathematical operator.
Do you ?

Use the numbers 2, 3, 4 and 5 and the symbols + and = to make a true equation. Conditions: Each must be used exactly once and no other numbers or symbols can be used.

Replace each alphabet with the number (1-9) to make the below equation correct.

AB * C = DE - F = GH / I

Using Only Five 5's and any mathematical operator make sum as 37

Can you make the number 24 by utilizing the numbers 1, 3, 4 and 6? You must use one number only one time and you can use mathematical operation symbols anytime anywhere.

Rectify the following equality 101 - 102 = 1 by moving just one digit.

What does this mathematical rebus means ?