Answer:
A = 6
Step-by-step explanation:
Given
5x³ + 35x² + 6x + 42 ( factor the first/second and third/fourth terms )
= 5x²(x + 7) + 6(x + 7) ← factor out (x + 7) from each term
= (x + 7)(5x² + 6) ← in factored form
Thus
(5x² + 6) → (5x² + A) ⇒ A = 6
