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1 tháng 8 2017

Câu hỏi là j?

1 tháng 8 2017

ko biet cau hoi

1 tháng 8 2017

m)\(x^4-256=\left(x^2\right)^2-16^2\)

\(=\left(x^2+16\right)\left(x^2-16\right)\)

\(=\left(x^2+16\right)\left(x+4\right)\left(x-4\right)\)

1 tháng 8 2017

h) \(15x\left(x-y\right)-25x+25y\)

\(=15x\left(x-y\right)-25\left(x-y\right)\)

\(=\left(x-y\right)\left(15x-25\right)\)

\(=5\left(x-y\right)\left(3x-5\right)\)

k) \(-y^2+\frac{1}{9}=\frac{1}{9}-y^2\)

\(=\left(\frac{1}{3}\right)^2-y^2\)

\(=\left(y+\frac{1}{3}\right)\left(\frac{1}{3}-y\right)\)

1) Ta có: \(x^2-2x-9y^2+6y\)

\(=x^2-2x+1-9y^2+6y-1\)

\(=\left(x-1\right)^2-\left(3y-1\right)^2\)

\(=\left(x-1-3y+1\right)\left(x-1+3y-1\right)\)

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

3) Ta có: \(x^2-9-4xy+4y^2\)

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

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

4) Ta có: \(\left(a+b\right)^2-\left(a-b\right)^2\)

\(=\left(a+b-a+b\right)\left(a+b+a-b\right)\)

\(=2b\cdot2a=4ab\)

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

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

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

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

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

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

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

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

7) Ta có: \(4x^2-12x-46\)

\(=\left(2x\right)^2-2\cdot2x\cdot3+9-55\)

\(=\left(2x-3\right)^2-55\)

\(=\left(2x-3-\sqrt{55}\right)\left(2x-3+\sqrt{55}\right)\)

27 tháng 10 2020

Bài 1:

a) \(2x^2y\left(3xy-4xy^2-\frac{3}{2xy^3}\right)\) \(=6x^3y^2-8x^2y^3-\frac{3x}{y^2}\)

b) \(\left(15x^4y^2-36x^3y^4+21x^2y^5\right):3x^2y^2\)\(=5x^2-12xy^2+7y^3\)

Bài 2:

a) \(x^2-4xy+4y^2-16\) \(=\left(x-2y\right)^2-16=\left(x-2y-4\right)\left(x-2y+4\right)\)

b) \(2x+xy-x^2-xy\) \(=x\left(2-x\right)\)

c)\(16x^2-25y^2=\left(4x-5y\right)\left(4x+5y\right)\)

b: \(=abx^2+ab+a^2x+b^2x\)

\(=bx\left(ax+b\right)+a\left(ax+b\right)\)

\(=\left(ax+b\right)\left(bx+a\right)\)

c: \(=\left(x-1\right)^3-8y^3\)

\(=\left(x-1-2y\right)\left(x^2-2x+1+2xy-2y+4y^2\right)\)

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

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

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

21 tháng 8 2018

a) \(36-12x+x^2\) \(=6^2-2.6.x+x^2\)

\(=\left(6-x\right)^2\)

b) \(4x^2+12x+9=\left(2x\right)^2+2.2x.3+3^2\)

\(=\left(2x+3\right)^2\)

c) \(-25x^6-y^8+10x^3y^4=-\left[25x^6-10x^3y^4+y^8\right]\)

\(=-\left[\left(5x^3\right)^2-2.5x^3.y^4+\left(y^4\right)^2\right]\)

\(=-\left(5x^3-y^4\right)^2\)

d) \(\dfrac{1}{4}x^2-5xy+25y^2=\left(\dfrac{1}{2}x\right)^2-2.\dfrac{1}{2}x.5y+\left(5y\right)^2\)

\(=\left(\dfrac{1}{2}x-5y\right)^2\)

Học tốt~~~

26 tháng 7 2018

a. \(36-12x+x^2=6^2-2.6.x+x^2=\left(6-x\right)^2\)

b. \(4x^2+12x+9=\left(2x\right)^2+2.2x.3+3^2=\left(2x+3\right)^2\)

c: \(=-\left(25x^6-10x^3y^4+y^8\right)\)

\(=-\left(5x^3-y^4\right)^2\)

d: \(=\left(\dfrac{1}{2}x\right)^2-2\cdot\dfrac{1}{2}x\cdot5y+\left(5y\right)^2=\left(\dfrac{1}{2}x-5y\right)^2\)