Question

How do you factor the trinomial `a^2 + 10a + 21`?

Answer 1

(a + 3)(a + 7)

Explanation:

`y = a^2+ 10a + 21`
Find 2 numbers knowing sum (10) and product (21).
Factor pairs of (21) -->...(3, 7). This sum is 10. Then, these 2 numbers are: 3 and 7.
y = (a + 3)(a + 7)