1.

Using the formula (a – b)2=(a2 – 2ab + b2), evaluate (689)2.

Answer»

Given (689)2

We have (a – b)2 = (a2 – 2ab + b2)(689)2 can be written as 700-11 So here a=700 and b=11

Using the formula,

(700 – 11)2 = (7002 – 2 X 700 X 11 + 112)

On simplifying we get

(700 – 11)2 = (490000 – 15400 +121)

(689)2 = 474721



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