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\(=\dfrac{\left(7x-y\right)\left(7x+y\right)}{7x-y}=7x+y\)

a: \(=3x^2-3y^2=3\left(x-y\right)\left(x+y\right)\)

b: \(=\left(4x^2-7x-50\right)^2-\left(16x^4+56x^3+49x^2\right)\)

\(=\left(4x^2-7x-50\right)^2-\left(4x^2+7x\right)^2\)

\(=\left(4x^2-7x-50-4x^2-7x\right)\left(4x^2-7x-50+4x^2+7x\right)\)

\(=\left(-14x-50\right)\left(8x^2-50\right)\)

\(=-4\left(7x+25\right)\left(2x-5\right)\left(2x+5\right)\)

d: \(=\left(x^2+y^2\right)^3-8x^3y^3\)

\(=\left(x^2+y^2-2xy\right)\left[x^4+2x^2y^2+y^4+2x^3y^2+2x^2y^3+4x^2y^2\right]\)

\(=\left(x-y\right)^2\cdot\left[x^4+y^4+6x^2y^2+2x^3y^2+2x^2y^3\right]\)

a) Ta có: \(\left(x^4+2x^2y^2+y^4\right):\left(x^2+y^2\right)\)

\(=\left(x^2+y^2\right)^2:\left(x^2+y^2\right)\)

\(=x^2+y^2\)

b) Ta có: \(\left(49x^2-81y^2\right):\left(7x+9y\right)\)

\(=\frac{\left(7x+9y\right)\left(7x-9y\right)}{7x+9y}\)

\(=7x-9y\)

c) Ta có: \(\left(x^3+3x^2y+3xy^2+y^3\right):\left(x+y\right)\)

\(=\left(x+y\right)^3:\left(x+y\right)\)

\(=\left(x+y\right)^2=x^2+2xy+y^2\)

d) Ta có: \(\left(x^3-3x^2y+3xy^2-y^3\right):\left(x^2-2xy+y^2\right)\)

\(=\left(x-y\right)^3:\left(x-y\right)^2\)

\(=\left(x-y\right)\)

e)Sửa đề: \(\left(8x^3+1\right):\left(2x+1\right)\)

Ta có: \(\left(8x^3+1\right):\left(2x+1\right)\)

\(=\frac{\left(2x+1\right)\left(4x^2-2x+1\right)}{2x+1}\)

\(=4x^2-2x+1\)

f) Ta có: \(\left(8x^3-1\right):\left(4x^2+2x+1\right)\)

\(=\frac{\left(2x-1\right)\left(4x^2+2x+1\right)}{4x^2+2x+1}\)

\(=2x-1\)

2 tháng 9 2020

a, (x4 + 2x2y2 + y4) : (x2 + y2)

= (x2 + y2)2 : (x2 + y2)

= x2 + y2

b, (49x2 - 81y2) : (7x + 9y)

= (7x - 9y)(7x + 9y) : (7x + 9y)

= 7x - 9y

c, (x3 + 3x2y + 3xy2 + y3) : (x + y)

= (x + y)3 : (x + y)

= (x + y)2

d, (x3 - 3x2y + 3xy2 - y3) : (x2 - 2xy + y2)

= (x - y)3 : (x - y)2

= x - y

Phần e thiếu thì phải

f, (8x3 - 1) : (4x2 + 2x + 1)

= (2x - 1)(4x2 + 2x + 1) : (4x2 + 2x + 1)

= 2x - 1

Chúc bn học tốt!

a: \(=3x^2-3y^2=3\left(x-y\right)\left(x+y\right)\)

c: \(=\left(x^2-y^2\right)^2-10\left(x^2-y^2\right)+25-4\left(x^2y^2+4xy+4\right)\)

\(=\left(x^2-y^2-5\right)^2-4\left(xy+2\right)^2\)

\(=\left(x^2-y^2-5-2xy-4\right)\left(x^2-y^2-5+2xy+4\right)\)

\(=\left(x^2-y^2-2xy-9\right)\left(x^2+2xy-y^2-1\right)\)

\(=\left(4x^2-7x-50\right)^2-x^2\left(16x^2+56x+49\right)\)

\(=\left(4x^2-7x-50\right)^2-x^2\left(4x+7\right)^2\)

\(=\left(4x^2-7x-50-4x^2-7x\right)\left(4x^2-7x-50+4x^2+7x\right)\)

\(=\left(-14x-50\right)\left(8x^2-50\right)\)

\(=-4\left(7x+25\right)\left(2x-5\right)\left(2x+5\right)\)

18 tháng 8 2017

= -2,5 nha chị

18 tháng 8 2017

(x2+y2-5)2-4x2y2-16xy-16

17 tháng 9 2017

a) \(3x^2-4y+4x-3y^2\)

\(=\left(3x^2-3y^2\right)-\left(4y-4x\right)\)

\(=3\left(x^2-y^2\right)-4\left(x+y\right)\)

\(=3\left(x-y\right)\left(x+y\right)-4\left(x+y\right)\)

\(=\left(x+y\right)\left(3\left(x-y\right)-4\right)\)

\(=\left(x+y\right)\left(3x-3y-4\right)\)

13 tháng 11 2017

a. x^3(x^2+1)^2-49x=x[x^2(x^2+1)^2-49) = x{[x(x+1)]^2-7^2}=x[(x^2+x)^2-7^2]= x(x^2+x-7)(x^2+x+7)

b. (x^2-9)^2+12(x-3)^2= (x-3)^2.(x+3)^2+ 12(x-3)^2=(x-3)^2.(x^2+6x+9)+12(x-3)^2 =(x-3)^2.(x^2+6x+9+12) = (x-3)^2.(x^2+6x+21)

c. (x-z)(x+z)-y(2x-y)= x^2-z^2-2xy+y^2 = (x^2-2xy+y^2)-z^2 =(x-y)^2-z^2=(x-y-z)(x-y+z)

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