Question

please solve the 20th
IF x + y =5 and x^2 + y^2 =111 then value of x^3 + y^3 is =?

Answer 1

here is your solution

Answer 2

x+y=5
[x+y]^2=5^2
x^2+y^2+2xy=25
111+2xy=25            {x^2+y^2=111}
xy=-43
[x+y]^3=5^3
x^3+y^3+3xy(x+y)=125
x^3+y^3=125+645=770