1 Thực hiện phép tính
a)(2x-3)(x-2)
b) (x+3)2
c) (2x-3y)3
d)2x(x3-8)
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\(2x\left(x^2-7x-3\right)=2x^3-14x-6x\)
\(4xy^2\left(-2x^3+y^2-7xy\right)=-8x^4y^2+4xy^5-28x^2y^3\)
\(a,2x\left(3x^2+1\right)=6x^3+2x\)
\(b,\left(2x^3-5x^2+6x\right):2=x^3-\dfrac{5}{2}x^2+3x\)
\(c,\left(x-3\right)\left(x+5\right)-x\left(x+2\right)=x^2+5x-3x-15-x^2-2x=-15\)
\(a,=4x^2+4x+1\\ b,=9-12y+4y^2\\ c,=\dfrac{x^2}{4}-xy+y^2\\ d,=\dfrac{25}{4}-5x+x^2\\ e,=4x^2+32xy+64y^2\\ f,=9x^2-30xy+25y^2\)
a,
$xy^2+x^2y+(-2xy^2)=xy^2-2xy^2+x^2y=-xy^2+x^2y$
b,
$12x^2y^3z^4+(-7x^2y^3z^4)=12x^2y^3z^4-7x^2y^3z^4=5x^2y^3z^4$
c,
$-6xy^3-(-6xy^3)+6x^3=-6xy^3+6xy^3+6x^3=0+6x^3=6x^3$
d,
$\frac{-x^2}{2}+\frac{7}{2}x^2+x=(\frac{7}{2}-\frac{1}{2})x^2+x$
$=3x^2+x$
e,
$2x^3+3x^3-\frac{1}{3}x^3=(2+3-\frac{1}{3})x^3=\frac{14}{3}x^3$
f,
$5xy^2+\frac{1}{2}xy^2+\frac{1}{4}xy^2=(5+\frac{1}{2}+\frac{1}{4})xy^2$
$=\frac{23}{4}xy^2$
\(a,=4x^2+12xy+9y^2\\ b,=25x^2-10xy+y^2\\ d,=4x^2+4xy^2+y^4\\ e,=9x^4-12x^2y+4y^2\\ g,=x^3+64\)
a,\(\dfrac{3-x}{x-5}+\dfrac{2x-8}{x-5}=\dfrac{3-x+2x-8}{x-5}=\dfrac{x-5}{x-5}=1\)
b, \(\dfrac{1}{x-y}+\dfrac{1}{x+y}+\dfrac{2x}{x^2-y^2}=\dfrac{x+y}{\left(x-y\right)\left(x+y\right)}+\dfrac{x-y}{\left(x-y\right)\left(x+y\right)}+\dfrac{2x}{\left(x-y\right)\left(x+y\right)}=\dfrac{x+y+x-y+2x}{\left(x-y\right)\left(x+y\right)}=\dfrac{4x}{\left(x-y\right)\left(x+y\right)}\)
a: \(\dfrac{4x^4y-7x^2y+3y}{-3x^2+2y}\)
\(=\dfrac{4x^4y-4x^2y-3x^2y+3y}{-\left(3x^2-2y\right)}\)
\(=\dfrac{4x^2y\left(x^2-1\right)-3y\left(x^2-1\right)}{-\left(3x^2-2y\right)}\)
\(=\dfrac{y\left(x^2-1\right)\left(4x^2-3\right)}{-\left(3x^2-2y\right)}\)
a) `(4x^4y-7x^2y+3y).(2y-3x^2y)`
`=8x^4y^2-14x^2y^2+6y^2-12x^6y^2+21x^4y^2-9x^2y^2`
`=29x^4y^2-12x^6y^2-23x^2y^2+6y^2`
b) `(x^2+3x-3/2 x^3):2x - x/2 . (1-3/2 x)`
`=(x+3-3/2 x^2):2 - (x/2 - 3/4 x^2)`
`=x/2 + 3/2 - 3/4 x^2 -x/2 +3/4 x^2`
`=3/2`
c) `(-2x^3-x-3+5x^2):(3-2x)`
`=(3-2x)(x^2-x-1) : (3-2x)`
`=x^2-x-1`
\(a,=4x^2-4x+1-4x^2+4-x^2-x+6=-x^2-5x+11\\ b,=8x^3+27-8x^3+72x=72x+27\)
\(\left(2x-3\right)\left(x-2\right)\)
\(=2x^2-4x-3x-6\)
\(=2x^2-7x-6\)
\(\left(x+3\right)^2\)
\(=x^2+2x.3+3^2\)
\(=x^2+6x+9\)
\(\left(2x-3y\right)^3\)
\(=\left(2x\right)^3-3.\left(2x\right)^2.3y+3.2x.\left(3y\right)^2-\left(3y\right)^3\)
\(=8x^3-36x^2y+54xy^2-27y^3\)
\(2x\left(x^3-8\right)\)
\(=2x^4-16x\)