Q13 of 59 Page 162

Simplify:

(i) (x + y)2 + (x – y)2;


(ii) (x + y)2 × (x – y)2.

(i) We use the formula (a + b)2 + (a - b)2 = 2(a2 + b2)


(x + y)2 + (x – y)2 = 2(x2 + y2)


(ii) Applying the formula (a + b)2(a - b)2 = (a2 - b2)2


(x + y)2 × (x – y)2 = (x2 - y2)2


⇒ (x + y)2 × (x – y)2 = x4-2x2y2 + y4


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