Question

How to solve this math problem

Answer 1

D. 1 and 20

Explanation:

To solve the equation, factor the quadratic and set the factors equal to 0.

d^2 - 21d + 20 becomes (d-20)(d-1) since -1*-20 = 20 and -1+-20 = -21.

Set each equal to 0 and solve for x.

d-20 = 0 d = 20

d - 1 = 0 d = 1