Given a & # 178; - AB = - 18, ab-b & # 178; = - 12, the values of the algebraic expressions a & # 178; - B & # 178; and a & # 178; - 2Ab + B & # 178; are obtained

Given a & # 178; - AB = - 18, ab-b & # 178; = - 12, the values of the algebraic expressions a & # 178; - B & # 178; and a & # 178; - 2Ab + B & # 178; are obtained

①a²-ab=-18,②ab-b²=-12
From formula (1) + formula (2), we can get a & # 178; - B & # 178; = - 30
From formula (1) - formula (2), we can get a & # 178; - 2Ab + B & # 178; = - 6
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