|
Question 848415: two numbers have the sum of one and a sum of cubes 31. what is the product?
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! two numbers have the sum of one
a + b = 1
a = (1-b)
and a sum of cubes 31.
a^3 + b^3 = 31
replace a with (1-b)
(1-b)^3 + b^3 = 31
FOIL (1-b)(1-b)(1-b) = 1 - 3b + 3b^2 - b^3
1 - 3b + 3b^2 - b^3 + b^3 = 31
a quadratic equation
3b^2 - 3b + 1 - 31 = 0
3b^2 - 3b - 30 = 0
using the quadratic formula, I got:
b = -2.70156212 then a = 3.70156212
or
b = 3.70156212 then a = -2.70156212
:
what is the product?
-2.70156212 * 3.70156212 = -10
|
|
|
| |
