Question

Cho x+y=20; x.y=-44. Tính A=x^5+y^5

thanks các bạn

Answer 1

Ta có: *x²+y²=(x+y)²-2xy=20²-2.(-44)=488

*x³+y³=(x+y)(x²-xy+y²)=20.[488-(-44)]=10640

Suy ra: (x²+y²)(x³+y³)=x⁵+x²y³+x³y²+y⁵=x⁵+y⁵+x²y².(x+y)

=>488.10640=x⁵+y⁵+(-44)².20

=>5192320=x⁵+y⁵+38720

=>x⁵+y⁵=5153600