Câu 1 :
a) `(-2x^2 - 5x + x^3)` + `(-1/2 x - 1/6 x^2 - x^3)`
= `-2x^2 - `5x` + `x^3` - `1/2 x` - `1/6 x^2` - `x^3`
= `(-2x^2 - 1/6 x^2)` + `(5x - 1/2 x)` + `(x^3 - x^3)`
= `-13/6 x^2` + `9/2 x`
b) `(-2x^2 - 5x + x^3)` - `(-1/2 x - 1/6 x^2 - x^3)`
= `-2x^2` - `5x` + `x^3` + `1/2 x` + `1/6 x^2` + `x^3`
= `(x^3 + x^3)` + `(-2x^2 + 1/6 x^2)` + `(-5x + 1/2 x)
= `6x^3` - `11/6 x^2` - `9/2 x`
@ximbui
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