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Bài 1:
a)\(5x^2y^3-25x^3y^4+10x^3y^3=5x^2y^3\left(1-5xy+2x\right)\)
b)\(x^3-2xy-x^2y+2y^2=\left(x^3-x^2y\right)-\left(2xy-2y^2\right)=x^2\left(x-y\right)-2y\left(x-y\right)=\left(x-y\right)\left(x^2-2y\right)\)
c)Đề sai hoàn toàn
d) \(2x^2+4xy+2y^2-8z^2=2\left(x^2+2xy+y^2-4z^2\right)=2\left[\left(x+y\right)^2-\left(2z\right)^2\right]=2\left(x+y-2z\right)\left(x+y+2z\right)\)e) \(3x-3a+yx-ya=3\left(x-a\right)+y\left(x-a\right)=\left(x-a\right)\left(3+y\right)\)
f)\(\left(x^2+y^2\right)^2-4x^2y^2=\left(x-y\right)^2\left(x+y\right)^2\)
g)\(2x^2-5x+2=2x^2-x-4x+2=x\left(2x-1\right)-2\left(2x-1\right)=\left(2x-1\right)\left(x-2\right)\)
i)\(14x\left(x-y\right)-21y\left(y-x\right)+28z\left(x-y\right)=14x\left(x-y\right)+21y\left(x-y\right)+28z\left(x-y\right)=7\left(x-y\right)\left(2x+3y+4z\right)\)
a: \(=5xy^2z^3=5\cdot2004\cdot\left(-2\right)^2\cdot5^3=5010000\)
b: \(=-\dfrac{1}{2}y^2=-\dfrac{1}{2}\cdot2^2=-2\)
a. \(x^3-2x^2+x\)
\(=x^3-x^2-x^2+x\)
\(=x^2\left(x-1\right)-x\left(x-1\right)\)
\(=\left(x-1\right)\left(x^2-x\right)\)
\(=\left(x-1\right)x\left(x-1\right)\)
\(=x\left(x-1\right)^2\)
b. \(x^2-2x-15\)
\(=\left(x^2-2x+1\right)-16\)
\(=\left(x-1\right)^2-4^2\)
\(=\left(x-1-4\right)\left(x-1+4\right)\)
\(=\left(x-5\right)\left(x-3\right)\)
c. \(5x^2y^3-25x^3y^4+10x^3y^3\)
\(=5x^2y^3\left(1-5xy+2x\right)\)
d. \(12x^2y-18xy^2-30y^2\)
\(=6y\left(2x^2-3xy-5y\right)\)
e. \(5\left(x-y\right)-y\left(x-y\right)\)
\(=\left(x-y\right)\left(5-y\right)\)
\(5x^2y^3-25x^2y^2+10x^2y^4=5x^2y^2\left(y-5+2y^2\right)\)
\(12a^4-24a^2b^2-6ab=6a\left(2a^3-4ab^2-3b\right)\)
mk chỉnh đề
\(-25x^6-y^8+10x^3y^4=-\left(5x^3-y^4\right)^2\)
\(25-\left(3-x\right)^2=\left(5-3+x\right)\left(5+3-x\right)=\left(2+x\right)\left(8-x\right)\)
\(3x^3y^2-6x^2y^3+9x^2y^2=3x^2y^2\left(x-2y+3\right)\)
\(5x^2y^3-25x^3y^4+10x^3y^3=5x^2y^3\left(1-5xy+2x\right)\)
\(12x^2y-18xy^2-3xy^2=3xy\left(4x-6y-y\right)\)
\(5\left(x-y\right)-y\left(x-y\right)=\left(x-y\right)\left(5-y\right)\)
\(y\left(x-z\right)+7\left(z-x\right)=y\left(x-z\right)-7\left(x-z\right)=\left(x-z\right)\left(y-7\right)\)
\(27x^2\left(y-1\right)-9x^3\left(1-y\right)=27x^2\left(y-1\right)+9x^3\left(y-1\right)=9x^2\left(y-1\right)\left(3-x\right)\)
bài 1
a) ta có: \(8x^3+12x^2y-2xy^2-3y^3\)
\(=\left(8x^3+12x^2y\right)-\left(2xy^2+3y^3\right)\)
\(=4x^2\left(2x+3y\right)-y^2\left(2x+3y\right)\)
\(=\left(2x+3y\right)\left(4x^2-y^2\right)\)
\(=\left(2x+3y\right)\left(2x-y\right)\left(2x+y\right)\)
\(a.x^2-y^2-5x+5y=\left(x-y\right)\left(x+y\right)-5\left(x-y\right)=\left(x-y\right)\left(x+y-5\right)\) \(b.5x^3-5x^2y-10x^2+10xy=5x^2\left(x-y\right)-10x\left(x-y\right)=5x\left(x-y\right)\left(x-2\right)\) \(c.x^3-2x^2-4xy^2+x=x\left(x^2-2x+1-4y^2\right)=x\left[\left(x-1\right)^2-4y^2\right]=\left(x-1-2y\right)\left(x-1+2y\right)\) \(d.\left(x+2\right)\left(x+3\right)\left(x+4\right)\left(x+5\right)-8=\left(x^2+7x+10\right)\left(x^2+7x+12\right)-8\)
Đặt : \(x^2+7x+11=t\) , ta có :
\(\left(t+1\right)\left(t-1\right)-8=t^2-1-8=\left(t-3\right)\left(t+3\right)=\left(x^2+7x+8\right)\left(x^2+7x+14\right)\)
\(e.2x^2-5x-7=2x^2+2x-7x-7=2x\left(x+1\right)-7\left(x+1\right)=\left(x+1\right)\left(2x-7\right)\) \(f.x^2-12x+36=\left(x-6\right)^2=\left(x-6\right)\left(x-6\right)\)
\(g.x^4-5x^2+4=x^4-x^2-4x^2+4=x^2\left(x^2-1\right)-4\left(x^2-1\right)=\left(x^2-1\right)\left(x^2-4\right)=\left(x+1\right)\left(x-1\right)\left(x+2\right)\left(x-2\right)\) \(g.a^3+b^3+c^3-3abc=\left(a+b\right)^3+c^3-3ab\left(a+b\right)-3abc=\left(a+b+c\right)\left[\left(a+b\right)^2-c\left(a+b\right)+c^2\right]-3ab\left(a+b+c\right)=\left(a+b+c\right)\left(a^2+2ab+b^2-ac-bc+c^2-3ab\right)=\left(a+b+c\right)\left(a^2+b^2+c^2-ab-bc-ac\right)\)
a, = (x + y)5 - (x5 + y5)
= (x + y)5 - (x + y)(x4 - x3y + x2y2 - xy3 + y4)
= (x + y) [(x + y)4 - x4 + x3y - x2y2 + xy3 - y4]
= (x + y) (5x3y + 5x2y2 + 5xy3)
= 5xy(x + y)(x2 + xy + y2)
b, = x(x2 - 5xy - 14y2)
= x(x2 - 7xy + 2xy - 14y2)
= x(x + 2y)(x - 7y)
a)
\(\dfrac{x^4+12x^2-5x}{-x}=-\dfrac{x^4}{x}-\dfrac{12x^2}{x}+\dfrac{-5x}{-x}=-x^3-12x+5\)
b)
\(\dfrac{15x^5y^9-10x^3y^5+25x^4y^4}{5x^2y^2}=\dfrac{15x^5y^9}{5x^2y^2}-\dfrac{10x^3y^5}{5x^2y^2}+\dfrac{25x^4y^4}{5x^2y^2}=3x^3y^7-2xy^3+5x^2y^2\)
`a)`
`(x^4 + 12x^2 -5x):(-x)`
`=[x^4 : (-x)] + [12x^2 : (-x)] - [5x:(-x)]`
`=-x^3 - 12x + 5`
`b)`
`(15 x^5 y^9 - 10 x^3 y^5 + 25 x^4 y^4) : 5x^2 y^2`
`=(15 x^5 y^9 : 5 x^2 y^2) - (10 x^3 y^5 : 5x^2 y^2) + (25 x^4 y^4 : 5 x^2 y^2)`
`=3 x^3 y^7 - 2 x y^3 + 5 x^2 y^2`