Let a and b be real numbers such that a^3+3ab^2=679 and 3a^2*b+b^3=-679. Find a+b.
Hi Guest!
If we added both equations we get:
a^3+3ab^2+3a^2b+b^3=0
Notice this is the expansion of a cubic.
Thus, (a+b)^3 = 0
So this means, a+b=0
I hope this helps :).
