Let a and b be real numbers such that a + b = -1. Compute a^2 - b^2 + 2a.
a + b = -1 ---> b = -1 - a
a2 - b2 + 2a = a2 - (-1 - a)2 + 2a = a2 - (1 + 2a + a2) + 2a = a2 - 1 - 2a - a2 + 2a = -1
Let a be -2 and b = 1
-2^2=4
1^2=1
2a=2
4-1+2=5
5 is the answer
