Question

这两道题怎么做？求大神解答

Answer 1

(1):a^2 - ab = 17，(2):ab - b^2 = 12
题目一：(1) + (2)有：
a^2 - ab + ab - b^2 = 17 + 12
a^2 - b^2 = 29;

题目二：(1) - (2)有：
a^2 - ab - ab + b^2 = 17 - 12
a^2 - 2ab + b^2 = 5;