Question

How to solve this equation (2a - 2) (a + 1) =0

Answer 1

Since the left side is a product of the two parenthetical terms, if either of them is equal to zero the equation is true, because anything time zero equal zero.  So the two solutions to that equation are when

2a-2=0

2a=2

a=1

and

a+1=0

a=-1

So the two solutions occur when a=-1 and 1

Answer 2

Since anything multiplied by zero produces zero, we can say 0(a + 1) = 0 and (2a - 2)(0) = 0.

Thus, 2a - 2 = 0 or a + 1 = 0
2a = 2
a = 1

a = -1

We can conclude that a = 1 or - 1 will produce the end result as 0.