Question

Find 100 × 95 by using suitable identity.

Answer 1

Let, 95 = 100-5
∴100×100-5
=(100 - √5)²
Using identity,(a+b)²=a²+2ab+b²
100²+(2 ×100×√5)+(√5)²
10000+200√5+5
10205√5

Answer 2

100 × 95
=(90+10)(90+5)
(x+a)(x+b) = x² + (a+b)x +ab
=90² + (10+5)90 + 10×5
=8100 + (15)90 + 50
=8100 + 1350 + 50
=9500

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