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27*29 = __________ (calculate without direct calculation).(a) 783(b) 753(c) 763(d) 793I had been asked this question by my school teacher while I was bunking the class.My question comes from Factorisation of Polynomials and Algebraic Identities in division Polynomials of Mathematics – Class 9

Answer» CORRECT ANSWER is (a) 783

The best explanation: We know that (a+b)*(a+c) = a^2 + (b+c)a + bc

27*29 can also be WRITTEN as (25+2)*(25+4)

Now using above identity, 27*29 = (25+2)*(25+4)

= 25^2 + (2+4)25 + (4)(2)

= 625 + 6(25) + 8

= 625 + 150 + 8

= 783.


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