Answer:
(z - 5)(7z - 3)
Explanation:
Given
7z² - 38z + 15
Consider the product of the factors of the coefficient of the z² term and the constant term which sum to give the coefficient of the z- term
product = 7 × 15 = 105 and sum = - 38
The factors are - 35 and - 3
Use these factors to split the z- term
7z² - 35z - 3z + 15 ( factor the first/second and third/fourth terms )
= 7z(z - 5) - 3(z - 5) ← factor out (z - 5) from each term
= (z - 5)(7z - 3) ← in factored form