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a) ( -5x2 +3xy + 7) + ( -6x2y + 4xy2 - 5)=4*x*y^2-6*x^2*y+3*a*x*y-5*a*x^2+7*a-5
b) ( 2,4x3 - 10x2y) + (7x2y - 2,4x3 + 3xy2)=3*x*y^2-3*x^2*y
c) ( 15x2y - 7xy2 - 6y2) + (2x2 - 12x2y + 7xy2)=-6*y^2+3*x^2*y+2*x^2
d) ( 4x2 + x2y - 5y3) + (5/3 x3 - 6xy2 - x2y) + (x3/3 + 10y3) + ( 6y3-15xy2 - 4x2y - 10x3)=11*y^3-21*x*y^2-4*x^2*y-8*x^3+4*x^2
a) \(6x^3-12x^2y^2+6xy^3=6x.\left(x^2-2xy^2+y^3\right)\)
b) \(\left(x^2+4\right)^2-16=\left(x^2+4-4\right)\left(x^2+4+4\right)=x^2\left(x^2+8\right)\)
c) \(5x^2-5xy-10x+10y=\left(5x^2-5xy\right)-\left(10x-10y\right)=5x\left(x-y\right)-10\left(x-y\right)\)
\(=\left(x-y\right)\left(5x-10\right)=5\left(x-y\right)\left(x-2\right)\)
d) \(a^3-3a+3b-b^3=\left(a^3-b^3\right)-\left(3a-3b\right)=\left(a-b\right)\left(a^2+ab+b^2\right)-3.\left(a-b\right)\)
\(=\left(a-b\right)\left(x^2+ab+b^2-3\right)\)
e) \(x^2-2x-y^2+1=\left(x^2-2x+1\right)-y^2=\left(x-1\right)^2-y^2=\left(x-1-y\right)\left(x-1+y\right)\)
f) \(x^2-x-2=x^2+x-2x-2=\left(x^2+x\right)-\left(2x+2\right)=x\left(x+1\right)-2\left(x+1\right)\)
\(=\left(x+1\right)\left(x-2\right)\)
g) \(x^4-5x^2+4=x^4-4x^2+4-x^2=\left(x^4-4x^2+4\right)-x^2=\left(x^2-2\right)^2-x^2\)
\(=\left(x^2-2-x\right)\left(x^2-2+x\right)\)
j) \(x^3-x^3-2x^2-x=-2x^2-x=-\left(2x^2+x\right)=-x\left(2x+1\right)\)
k) \(\left(a^3-27\right)-\left(3-a\right)\left(6a+9\right)=\left(a-3\right).\left(a^2+3a+9\right)+\left(a-3\right)\left(6a+9\right)\)
\(\left(a-3\right)\left(a^2+3a+9+6a+9\right)=\left(a-3\right)\left(a^2+9a+18\right)\)
h) \(x^2\left(y-z\right)+y^2\left(z-x\right)+z^2\left(x-y\right)\)
\(=x^2y-x^2z+y^2z-y^2x+z^2x-z^2y\)
\(=\left(x^2y-y^2x\right)-\left(x^2z-y^2z\right)+\left(z^2x-z^2y\right)\)
\(=xy\left(x-y\right)-z\left(x^2-y^2\right)+z^2\left(x-y\right)\)
\(=xy\left(x-y\right)-z\left(x-y\right)\left(x+y\right)+z^2\left(x-y\right)\)
\(=\left(x-y\right)\left(xy-zx-zy+z^2\right)\)
\(=\left(x-y\right)\left[\left(xy-zx\right)-\left(zy-z^2\right)\right]\)
\(=\left(x-y\right)\left[x\left(y-z\right)-z\left(y-z\right)\right]\)
\(\left(x-y\right)\left(y-z\right)\left(x-z\right)\)
a) x2 + 6x + 9 = x2 + 2 . x . 3 + 32 = (x + 3)2
b) 10x – 25 – x2 = -(-10x + 25 +x2) = -(25 – 10x + x2)
= -(52 – 2 . 5 . x – x2) = -(5 – x)2
c) 8x3 - 1/8 = (2x)3 – (1/2)3 = (2x - 1/2)[(2x)2 + 2x . 12 + (1/2)2]
= (2x - 1/2)(4x2 + x + 1/4)
d)1/25x2 – 64y2 = (1/5x)2(1/5x)2- (8y)2 = (1/5x + 8y)(1/5x - 8y)
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. \(5\left(x-y\right)-y\left(x-y\right)\)
\(=\left(x-y\right)\left(5-y\right)\)
\(\text{a) }x^3y^3+x^2y^2+4\)
\(=x^3y^3+2x^2y^2-x^2y^2+4\)
\(=\left(x^3y^3+2x^2y^2\right)-\left(x^2y^2-4\right)\)
\(=x^2y^2\left(xy+2\right)-\left(xy+2\right)\left(xy-2\right)\)
\(=\left(xy+2\right)\left(x^2y^2-xy+2\right)\)
\( {c)}\)\(x^4+x^3+6x^2+5x+5\)
\(=\left(x^4+x^3+x^2\right)+\left(5x^2+5x+5\right)\)
\(=x^2\left(x^2+x+1\right)+5\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^2+5\right)\)
\({d)}\)\(x^4-2x^3-12x^2+12x+36\)
\(=\left(x^4-2x^3-6x^2\right)-\left(6x^2-12x-36\right)\)
\(=x^2\left(x^2-2x-6\right)-6\left(x^2-2x-6\right)\)
\(=\left(x^2-2x-6\right)\left(x^2-6\right)\)
Câu b sai đề thì phải ah
\(a.x^2-y^2-5x+5y=\left(x-y\right)\left(x+y\right)-5\left(x-y\right)=\left(x-y\right)\left(x+y-5\right)\) \(b.5x^3-5x^2y-10x^2+10xy=5x^2\left(x-y\right)-10x\left(x-y\right)=5x\left(x-y\right)\left(x-2\right)\) \(c.x^3-2x^2-4xy^2+x=x\left(x^2-2x+1-4y^2\right)=x\left[\left(x-1\right)^2-4y^2\right]=\left(x-1-2y\right)\left(x-1+2y\right)\) \(d.\left(x+2\right)\left(x+3\right)\left(x+4\right)\left(x+5\right)-8=\left(x^2+7x+10\right)\left(x^2+7x+12\right)-8\)
Đặt : \(x^2+7x+11=t\) , ta có :
\(\left(t+1\right)\left(t-1\right)-8=t^2-1-8=\left(t-3\right)\left(t+3\right)=\left(x^2+7x+8\right)\left(x^2+7x+14\right)\)
\(e.2x^2-5x-7=2x^2+2x-7x-7=2x\left(x+1\right)-7\left(x+1\right)=\left(x+1\right)\left(2x-7\right)\) \(f.x^2-12x+36=\left(x-6\right)^2=\left(x-6\right)\left(x-6\right)\)
\(g.x^4-5x^2+4=x^4-x^2-4x^2+4=x^2\left(x^2-1\right)-4\left(x^2-1\right)=\left(x^2-1\right)\left(x^2-4\right)=\left(x+1\right)\left(x-1\right)\left(x+2\right)\left(x-2\right)\) \(g.a^3+b^3+c^3-3abc=\left(a+b\right)^3+c^3-3ab\left(a+b\right)-3abc=\left(a+b+c\right)\left[\left(a+b\right)^2-c\left(a+b\right)+c^2\right]-3ab\left(a+b+c\right)=\left(a+b+c\right)\left(a^2+2ab+b^2-ac-bc+c^2-3ab\right)=\left(a+b+c\right)\left(a^2+b^2+c^2-ab-bc-ac\right)\)
\(5x^2y^3-25x^2y^2+10x^2y^4=5x^2y^2\left(y-5+2y^2\right)\)
\(12a^4-24a^2b^2-6ab=6a\left(2a^3-4ab^2-3b\right)\)
mk chỉnh đề
\(-25x^6-y^8+10x^3y^4=-\left(5x^3-y^4\right)^2\)
\(25-\left(3-x\right)^2=\left(5-3+x\right)\left(5+3-x\right)=\left(2+x\right)\left(8-x\right)\)