Answer:
(x - 1)(7x + 4)
Explanation:
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 = 7 × - 4 = - 28 and sum = - 3
The factors are - 7 and + 4
Use these factors to split the x- term
7x² - 7x + 4x - 4 ( factor first/second and third/fourth terms )
= 7x(x - 1) + 4(x - 1) ← factor out (x - 1) from each term
= (x - 1)(7x + 4) ← in factored form