Using the formula

Question:

Using the formula (a − b)2 = (a2 − 2ab + b2), evaluate:

(i) (196)2

(ii) (689)2

(iii) (891)2

Solution:

(i) $(196)^{2}=(200-4)^{2}=200^{2}-2(200 \times 4)+4^{2}=40000-1600+16=38416$

(ii) $(689)^{2}=(700-11)^{2}=700^{2}-2(700 \times 11)+11^{2}=490000-15400+121=474721$

(iii) $(891)^{2}=(900-9)^{2}=900^{2}-2(900 \times 9)+9^{2}=810000-16200+81=793881$

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