Question

a) Làm phép tính \(\left(15+5x^2-3x^2-9x\right):\left(5-3x\right)\)

b) t bằng mấy để \(x^3-3x^2+t-4x⋮\left(1+x+x^2\right)\)

Answer 1

a) \(\left(15+5x^2-3x^2-9x\right):\left(5-3x\right)\)

\(=\dfrac{2x^2-9x+15}{5-3x}\)

b) \(x^3-3x^2+t-4x⋮\left(1+x+x^2\right)\)

\(\Rightarrow x^3+x^2+x-4x^2-5x+t⋮x^2+x+1\)

\(\Rightarrow x\left(x^2+x+1\right)-4x^2-5x+t⋮x^2+x+1\)

\(\Rightarrow x\left(x^2+x+1\right)-4\left(x^2+x+1\right)-x+4+t⋮x^2+x+1\)

\(\Rightarrow\left(x-4\right)\left(x^2+x+1\right)-\left(x-4\right)+t⋮x^2+x+1\)

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