Let a and b be real numbers such that a + b = -1. Compute a^2 - b^2 + 2a.
The answer can be written out as an expression in terms of a alone or b alone. You need to know either the value of a or b in order to know the exact value of a2−b2+2a.
a2−b2+2a
=(a+b)(a−b)+2a
=−1(a−b)+2a
=−a−(−b)+2a
=b−a+2a
=b+a
=−1
You're right. I made an incorrect observation.
