Question

if a+b =5 ab =6 then
${a}^{3} + {b}^{3} =$

Answer 1

ab = 6 -------(1)

a +b = 5 -------(2)

On squaring both sides, we get

a^2 + b^2 + 2ab = 25

=> a^2 + b^2 + 2×6 = 25

=> a^2 + b^2 = 25 - 12

=> a^2 + b^2 = 13 ---------(3)

Now,

a^3 +b^3 = (a+b) (a^2 +b^2 - ab)

= (5)( 13 - 6)

= 5 × 7

= 35

Answer 2

Hi,

Please see the attached file!



Thanks