Answer:
(x - 1)(2x + 1)
Explanation:
Given
2x² - x - 1
Consider the factors of the product of the coefficient of the x² term and the constant term which sum to give the coefficient of the x- term.
product = 2 × - 1 = - 2 and sum = - 1
The factors are - 2 and + 1
Use these factors to split the x- term
2x² - 2x + x - 1 ( factor the first/second and third/fourth terms )
2x(x - 1) + 1 (x - 1) ← factor out (x - 1) from each term
= (x - 1)(2x + 1) ← in factored form