\(\left(3xy-x^2+y\right)\dfrac{2}{3}x^2y=2x^3y^2-\dfrac{2}{3}x^4y+\dfrac{2}{3}x^2y^2\)
\(x^2\left(4x^3-5xy+2x\right)\left(\dfrac{-1}{2}xy\right)=\left(4x^5-5x^3y+2x^3\right)\left(\dfrac{-1}{2}xy\right)=-2x^6y\cdot\dfrac{5}{2}x^4y^2-x^4y\)
bài 2
\(3x\left(12x-4\right)-9x\left(4x-3\right)=30\)
\(=36x^2-12x-36x^2+27x=5x=30=>x=6\)
\(x\left(5-2x\right)+2x\left(x-1\right)=15\)
\(=5x-2x^2+2x^2-2x=3x=15=>x=5\)
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