Question

Answer 1

a: Ta có: x=49

nên x+1=50

Ta có: \(A=x^4-50x^3+50x^2-50x+4\)

\(=x^4-x^3\left(x+1\right)+x^2\left(x+1\right)-x\left(x+1\right)+4\)

\(=x^4-x^4-x^3+x^3+x^2-x^2-x+4\)

=4-x

=4-49

=-45

Answer 2

b: Ta có: x=8

nên x+1=9

Ta có: \(B=x^{100}-9x^{99}+9x^{98}-9x^{97}+...+9x^2-9x+10\)

\(=x^{100}-x^{99}\left(x+1\right)+x^{98}\left(x+1\right)-x^{97}\left(x+1\right)+...+x^2\left(x+1\right)-x\left(x+1\right)+10\)

\(=x^{100}-x^{100}-x^{99}+x^{99}+x^{98}-x^{98}+...+x^3+x^2-x^2-x+10\)

=-x+10

=-8+10

=2