Question

what is the answer to this problem.

Answer 1

2y^2 - y - 1 = 0
(2y + 1) (y - 1) = 0 
2y + 1 = 0    or    y - 1 = 0
y = -1/2        or    y = 1

Answer 2

When you factor this, you should get ( y - 1 )( 2y + 1 ) One of these inside the parenthesis has to equal 0, so the answer is either 1 or -1/2.