+214 Let a and b be nonzero complex numbers such that |a|=|b|=|a+b|.
Find the sum of all possible values of ab.
Since ∣a∣=∣b∣=∣a+b∣, we have ∣a∣2=∣b∣2=∣a+b∣2. This gives us the following equations:
a^2 = b^2 a^2 + b^2 = (a + b)^2
The first equation tells us that a and b are of equal magnitude. The second equation tells us that a2+b2=a2+2ab+b2, or 2ab=0. This means that a and b are either equal or opposite in sign.
If a and b are equal, then a/b=1. If a and b are opposite in sign, then a/b=−1. The sum of all possible values of a/b is therefore 1−1=0.
