Answer:
Below in bold.
Step-by-step explanation:
y^2 - 3y - 40
To factor this we need 2 numbers whose product is -40 and whose sum is -3. These are -8 and +5. so the factors are:
(y - 8)(y + 5).
3x^2 + 10x + 3
To factor this we need 2 numbers whose product is (3*3) = +9 and whose sum is +10. These are +9 and +1 so we write:
3x^2 + 9x + x + 3
Factor by grouping:
= 3x(x + 3) + 1(x + 3)
= (3x + 1)(x + 3).
