question_answer 1)

If  \[a=2,b=-2\], find the value of : (i) \[{{a}^{2}}+{{b}^{2}}\]                              (ii) \[{{a}^{2}}+ab+{{b}^{2}}\]                     (iii) \[{{a}^{2}}-{{b}^{2}}\].

Answer:

                (i) \[{{a}^{2}}+{{b}^{2}}={{(2)}^{2}}+{{(-2)}^{2}}=4+4=8\]                 (ii) \[{{a}^{2}}+ab+{{b}^{2}}={{(2)}^{2}}+(2)(-2)+{{(-2)}^{2}}\]                 \[=4-4+4=4+4-4\]                 \[=8-4=4.\]                 (iii) \[{{a}^{2}}-{{b}^{2}}={{(2)}^{2}}-{{(-2)}^{2}}=4-4=0\].