# If a + B = 10 and Ab = 21, Find the Value of A3 + B3 - Mathematics

If a + b = 10 and ab = 21, find the value of a3 + b3

#### Solution

In the given problem, we have to find the value of  a^3 + b^3

Given a+b = 10, ab = 21

We shall use the identity (a+b)^3 = a^3 +b^3 +3ab(a+b)

Here putting, a+b = 10,ab= 21

(10)^3 = a^3+ b^3 +3 (21)(10)

 1000 = a^3 +b^3 +630

1000 - 630 = a^3 +b^3

370 = a^3 + b^3

Hence the value of  a^3 +b^3 is  370.

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#### APPEARS IN

RD Sharma Mathematics for Class 9
Chapter 4 Algebraic Identities
Exercise 4.3 | Q 2 | Page 19