SOLUTION: The sum of two numbers is 20 and their product is 15. find the sum of their cubes?

Algebra ->  Expressions-with-variables -> SOLUTION: The sum of two numbers is 20 and their product is 15. find the sum of their cubes?      Log On


   

Question 938052: The sum of two numbers is 20 and their product is 15. find the sum of their cubes?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
The sum of two numbers is 20: numbers x and 20-x
and their product is 15.
x(20-x) = 15
20x - x^2 = 15
x^2 - 20x + 15 = 0 Format ax^2+ bx + c
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
x = 10 ± √85
(10+√85)^3 + (10-√85)^3 Use Calculator