Question

95^3 = __________ (calculate without direct calculation).

(a) 856395

(b) 857625

(c) 857375

(d) 852395

I have been asked this question during an interview.

My query is from Factorisation of Polynomials and Algebraic Identities topic in portion Polynomials of Mathematics – Class 9

Answer 1

The correct option is (c) 857375

Easy explanation: We know that (x-y)^3 = x^3– y^3 – 3 xy (x-y).

95^3  can also be written as (100-5)^3

Therefore, 95^3= (100-5)^3 = (100)^3 – (5)^3 – 3(100)(5)(100-5)

= 1000000 – 125 – 1500(95)

= 1000000 – 125 – 142500

= 857375.