Q2 of 59 Page 263

Evaluate the following by using suitable identities:

109×108

Given:109×108 = (100 + 9)(100 + 8)

= (100)2 + (9 + 8)100 + (9×8),


where x = 100,a = 9 and b = 8 in identity (x + a)(x + b) = x2 + (a + b)x + ab


= 10000 + 1700 + 72


= 11772


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