Question

If a+b=11,ab=28,Find he value of xcube-ycube

Answer 1

Given a+b=11 and ab =28 (a-b)^2=(a+b)^2-4ab =11×11-4×28 =121-112 =9 (a-b)=root 9 =3 Now a^3-b^3=(a-b)^3+3ab (a-b) =3×3×3+3×28×3 =27+252=279