The 1st thing you do is to:

Simplify [(2x^2+x-1)/(4x^2-1)]

2nd:

Find the common factor [(2x-1)(x+1)/(2x-1)(2x-1)]

3rd:

Cancel (2x-1) on the top & on the bottom of your partial answer giving you this partial answer of [(x+1)/(2x-1)]

4th:

Simplify [(x-3)/(x^2-2x-3)]

5th:

Find the common factor[(x-3)/(x+1)(x-3)]

6th:

Cancel (x-3) on the top & on the bottom of your partial answer giving you this partial answer of [1/(x+1)]

7th:

Multiply both [(x+1)/(2x-1)] & [1/(x+1)]

8th:

Cancel both (x+1) to give you a final answer of:

[1/(2x-1)]

[(2x^2+x-1)/(4x^2-1)]*[(x-3)*(x^2-2x-3)]

Then the answer is (x-1)/(2x+1)(x-3)

Here are the factors:

[(2x-1)(x+1)/(2x-1)(2x+1)]*[(x-1)/(x-3)(x+1)]

= [( 2x+1)( x-1) / (2x+1)(2x-1)] * (x-3)/X^2

=[(x-1)/(2x-1) * (x-3)/(x^2)

= [(x-1)(x-3) / (x^2)(2x-1)

should first simplify da (2x^2 +x-1).

tn u know that, a^2 – b^2 = (a+b)(a-b)