Answer:The answer is 3 & 7
Step-by-step explanation:3 x 7 = 21
3 + (7) = 10
Are you asking because you are trying to figure out how to factor the following quadratic equation?
x2 + 10x + 21 = 0
If so, the solution to factor the quadratic equation above is:
(X + 3 ) (X + 7)
To summarize, since 3 and 7 multiply to 21 and add up 10, you know that the following is true:
x2 + 10x + 21 = (X + 3 ) (X + 7)