\(\left(-2x^3-\dfrac{1}{4}y-4yz\right).8xy^2\)
\(=-2x^3.8xy^2-\dfrac{1}{4}y.8xy^2-4yz.8xy^2\)
\(=-16x^4y^2-2xy^3-32xy^3z\)
Chúc bạn học tốt!!!
\(-\dfrac{1}{3}xz\left(-9xy+15yz\right)+3x^2\left(2yz^2-yz\right)\)
\(=-\dfrac{1}{3}xz\cdot-9xy+-\dfrac{1}{3}xz\cdot15yz+3x^2\cdot2yz^2-3x^2\cdot yz\)
\(=\left(-\dfrac{1}{3}\cdot-9\right)\left(x\cdot x\right)yz+\left(-\dfrac{1}{3}\cdot15\right)xy\left(z\cdot z\right)+\left(3.2\right)\left(x^2\cdot yz^2\right)-3\left(x^2\cdot yz\right)\)
=\(3x^2yz+-5xyz^2+6x^2yz^2-3x^2yz\)
\(=\left(3x^2yx-3x^2yx\right)-5x^2yz^2+6x^2yz\)
\(=-5x^2yz^2+6x^2yz\)
1. \(-\dfrac{1}{3}xz\left(-9xy+15yz\right)+3x^2\left(2yz^2-yz\right)\)
\(=3x^2yz-5xyz^2+6x^2yz^2-3x^2yz\)
2.
\(\left(-2x^3-\dfrac{1}{4}y-4yz\right)8xy^2=-16x^4y^2-2xy^3-32xy^3z\)
3.
\(3x^2-3x+4x\left(1-\dfrac{1}{2}x\right)=3x^2-3x+4x-2x^2=\left(3x^2-2x^2\right)+\left(-3x+4x\right)=x^2+x\)
\(2x^2-3x+4x\left(1-\dfrac{1}{2}x\right)\)
\(=2x^2-3x+4x-4x.\dfrac{1}{2}x\)
\(=2x^2-3x+4x-2x^2\)
\(=\left(2x^2-2x^2\right)+\left(-3x+4x\right)=x\)
Chúc bạn học tốt!!!
\(\left(-2x^3-\dfrac{1}{4}y-4yz\right)8xy^2\)
\(=-2x^3\cdot8xy^2-\dfrac{1}{4}y\cdot8xy^2-4yz\cdot8xy^2\)
\(=\left(-2\cdot8\right)\left(x^3\cdot x\right)y-\left(\dfrac{1}{4}\cdot8\right)\left(y\cdot y^2\right)x-\left(4\cdot8\right)\left(y\cdot y^2\right)zx\)
\(=-16x^4y-2y^3x-32y^3zx\)
\(2x^2-3x+4x\left(1-\dfrac{1}{2}x\right)\)
\(=2x^2-3x+4x-4x\cdot\dfrac{1}{2}x\)
\(=2x^2-3x+4x-\left(4\cdot\dfrac{1}{2}\right)\left(x\cdot x\right)\)
\(=2x^2-3x+4x-2x^2\)
\(=\left(2x^2-2x^2\right)+\left(-3x+4x\right)\)
\(=x\)
