Question

a)Tính các GT các biểu thức sau:\(B=x^3-y^2+x+x^2y-2x^2+2021+3y-x\text{y}\) với x+y=2

 

Answer 1

`B=x^3-y^2+x+x^2y-2x^2+2021+3y-xy`

`=(x^3+x^2y)+(-xy-y^2)+x+3y-2x^2+2021`

`=x^2(x+y)-y(x+y)+x+3y-2x^2+2021`

`=2x^2-2y+x+3y-2x^2+2021`

`=(2x^2-2x^2)+x+(3y-2y)+2021`

`=x+y+2021`

`=2+2021`

`=2023` 

Answer 2

\(B=\left(x^3+x^2y\right)-\left(y^2+xy\right)-2x^2+x+3y+2021=\)

\(=x^2\left(x+y\right)-y\left(x+y\right)-2x^2+x+3y+2021=\)

\(=2x^2-2y-2x^2+x+3y+2021=\)

\(=x+y+2021=2023\)