Question

Tính giá trị biểu thức:

M = x^4 - 2x^3 + 3x^2 - 2x + 2 với x^2 - x = 4

Answer 1

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

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

\(=x^2\left(x^2-x\right)-x\left(x^2-x\right)+ 2\left(x^2-x\right)+2\)

\(=\left(x^2-x\right)\left(x^2-x+2\right)+2\)

Thay  \(x^2-x=4\)vào  M ta đc:

\(M=4.\left(4+2\right)+2\)

\(=4.6+2\)

\(=26\)

Answer 2

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

   = x^2.(x^2-x)-x.(x^2-x)+2.(x^2-x)+2

   = (x^2-x).(x^2-x+2)+2

Thay x^2-x=4 thì :

M = 4.(4+2)+2 = 26

Tk mk nha