Question

4
If the sum of two numbers is 13 and the sum of their squares is 81, then the sum
of their cubes will be:
1481
2) 462
3) 361
4) 652​

Answer 1

Answer:

let the numbers are x and y

so, x+y=13

again , x^2+y^2=81

=> (x+y)^2-2xy=81

=> (13)^2-2xy=81

=> 169-81=2xy

=> 88=2xy

=> xy=88/2

=> xy=44

so,

x^3+y^3

=(x+y)^3-3xy(x+y)

=(13)^3-3.44.13

=13(169-132)

=13×37

=481