I have no idea what to do here:
If ab = 10 and a^2 + b^2 = 40, then find (a + b)^4 - (a - b)^4.
+129849 ab =10
a^2 + b^2 = 40
( a + b)^4 = a^4 + 4a^3b + 6a^2b^2 + 4ab^3 + b^4 (1)
(a - b)^4 = a^4 - 4a^3b + 6a^2b^2 - 4ab^3 + b^4 (2)
Subtract (2) from (1) and we get that
8a^3b + 8ab^3 = 8(ab)( a^2 + b^2)
Now....just fill in what we know
8 (ab) (a ^2 + b^2) =
8 (10) (40) =
3200
