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\(\frac{12}{5}x^2y^2-9x^4-\frac{4}{25}y^4\)
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1, \(x^2-y^2-2x+2y=\left(x-y\right)\left(x+y\right)-2\left(x-y\right)=\left(x+y-2\right)\left(x-y\right)\)
2, \(x^2-25+y^2+2xy=\left(x+y\right)^2-5^2=\left(x+y-5\right)\left(x+y+5\right)\)
3, \(x^2y-x^3-9y+9x=x^2\left(y-x\right)-9\left(y-x\right)=\left(x-3\right)\left(x+3\right)\left(y-x\right)\)
4, \(x^4+2x^3+x^2=x^2\left(x^2+2x+1\right)=x^2\left(x+1\right)^2\)
5, \(x^4+8x=x\left(x^3+8\right)=x\left(x+8\right)\left(x^2-8x+64\right)\)
\(1,\)
\(x^2-y^2-2x+2y\)
\(=\left(x^2-y^2\right)-\left(2x-2y\right)\)
\(=\left(x-y\right)\left(x+y\right)-2\left(x-y\right)\)
\(=\left(x-y\right)\left(x+y-2\right)\)
\(2,\)
\(x^2-25+y^2+2xy\)
\(=\left(x^2+2xy+y^2\right)-25\)
\(=\left(x+y\right)^2-5^2\)
\(=\left(x+y-5\right)\left(x+y+5\right)\)
\(3,\)
\(x^2y-x^3-9y+9x\)
\(=\left(x^2y-x^3\right)-\left(9y-9x\right)\)
\(=x^2\left(y-x\right)-9\left(y-x\right)\)
\(=\left(x^2-9\right)\left(y-x\right)\)
\(=\left(x-3\right)\left(x+3\right)\left(y-x\right)\)
\(4,\)
\(x^4+2x^3+x^2\)
\(=x^2\left(x^2+2x+1\right)\)
\(=x^2\left(x+1\right)^2\)
\(5,\)
\(x^4-8x\)
\(=x\left(x^3-8\right)\)
\(=x\left(x-2\right)\left(x^2+2x+4\right)\)
b: \(=\dfrac{12\left(y-z\right)^4+3\left(y-z\right)^5}{6\left(y-z\right)^2}=2\left(y-z\right)^2+\dfrac{1}{2}\left(y-z\right)^3\)
a) = (3x)^2 + 2.3x.5+ 5^2 = (3x+5)^2
b) = (2/3x)^2-(4y)^2=(2/3x-4y)(2/3x+4y)
c) = -(9x^4-12/5x^2y^2+4/25y^4) = -[(3x^2)^2 - 2.3x^2.2/5y^2 + (2/5y^2)^2]= -(3x^2-2/5y^2)^2
d) = (x-5)^2 - 4^2= (x-5+4)(x-5-4) = (x-1)(x-9)
e) = (2x)^3 + 3.(2x)^2.(5y) + 3.(2x).(5y)^2 + (5y)^3 = (2x+5y)^3
f) = (8x)^2 - (8a+b)^2 = (8x-8a-b)(8x+8a+b)
g) = (7x-4-2x-1)(7x-4+2x+1) = (5x-5)(9x-3) = 5(x-1).3(x-3)=15(x-1)(x-3)
h) = (x-y)(x+y)- 2(x+y) = (x+y)(x-y-2)
# Chúc bạn học tốt #
a: \(=5x\left(xy^2+3x+6y^2\right)\)
b: \(=\left(x-2\right)\left(x+3\right)-\left(x-2\right)\left(x+2\right)=\left(x-2\right)\left(x+3-x-2\right)=\left(x-2\right)\)
c: \(=\left(x-3\right)\left(x-4\right)\)
d: \(=x\left(x^2-2xy+y^2-9\right)\)
=x(x-y-3)(x-y+3)
e: \(=\left(x+y\right)^2-25=\left(x+y+5\right)\left(x+y-5\right)\)
f: \(=\left(x-4\right)\left(x+3\right)\)
\(1,\\ a,=4\left(x-2\right)^2+y\left(x-2\right)=\left(4x-8+y\right)\left(x-2\right)\\ b,=3a^2\left(x-y\right)+ab\left(x-y\right)=a\left(3a+b\right)\left(x-y\right)\\ 2,\\ a,=\left(x-y\right)\left[x\left(x-y\right)^2-y-y^2\right]\\ =\left(x-y\right)\left(x^3-2x^2y+xy^2-y-y^2\right)\\ b,=2ax^2\left(x+3\right)+6a\left(x+3\right)\\ =2a\left(x^2+3\right)\left(x+3\right)\\ 3,\\ a,=xy\left(x-y\right)-3\left(x-y\right)=\left(xy-3\right)\left(x-y\right)\\ b,Sửa:3ax^2+3bx^2+ax+bx+5a+5b\\ =3x^2\left(a+b\right)+x\left(a+b\right)+5\left(a+b\right)\\ =\left(3x^2+x+5\right)\left(a+b\right)\\ 4,\\ A=\left(b+3\right)\left(a-b\right)\\ A=\left(1997+3\right)\left(2003-1997\right)=2000\cdot6=12000\\ 5,\\ a,\Leftrightarrow\left(x-2017\right)\left(8x-2\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=2017\\x=\dfrac{1}{4}\end{matrix}\right.\\ b,\Leftrightarrow\left(x-1\right)\left(x^2-16\right)=0\Leftrightarrow\left[{}\begin{matrix}x=1\\x=4\\x=-4\end{matrix}\right.\)
Đặt \(A=x^4-2y^4-x^2y^2+x^2+y^2\)
\(\Rightarrow2A=2x^4-4y^4-2x^2y^2+2x^2+2y^2\)
\(\Rightarrow2A=\left(x^4+2x^2+1\right)-\left(y^4-2y^2+1\right)\)\(+\left(x^4-2x^2y^2+y^4\right)-4y^4\)
\(\Rightarrow2A=\left(x^2+1\right)^2-\left(y^2-1\right)^2+\left(x^2-y^2\right)^2-4y^4\)
\(\Rightarrow2A=\left[\left(x^2+1\right)^2-4y^4\right]+\left[\left(x^2-y^2\right)^2-\left(y^2-1\right)^2\right]\)
\(\Rightarrow2A=\left(x^2+1-2y^2\right)\left(x^2+1+2y^2\right)+\)\(\left(x^2-y^2+y^2-1\right)\left(x^2-y^2-y^2+1\right)\)
\(\Rightarrow2A=\left(x^2+1-2y^2\right)\left(x^2+1+2y^2\right)+\)\(\left(x^2-1\right)\left(x^2+1-2y^2\right)\)
\(\Rightarrow2A=\left(x^2+1-2y^2\right)\left(x^2+1+2y^2+x^2-1\right)\)
\(\Rightarrow2A=\left(x^2-2y^2+1\right)\left(2x^2+2y^2\right)\)
\(\Rightarrow2A=2\left(x^2-2y^2+1\right)\left(x^2+y^2\right)\)
\(\Rightarrow A=\left(x^2-y^2+1\right)\left(x^2+y^2\right)\)
Nhầm, tớ chốt lại: \(A=\left(x^2-2y^2+1\right)\left(x^2+y^2\right)\), đừng xem cái câu cuối ở tin 1, sai đấy.
\(\frac{12}{5}x^2y^2-9x^4-\frac{4}{25}y^4\)
\(=-\left(\frac{4}{25}y^4-\frac{12}{5}x^2y^2+9x^4\right)\)
\(=-\left[\left(\frac{2}{5}y^2\right)^2-2\cdot\frac{2}{5}y^2\cdot3x^2+\left(3x^2\right)^2\right]\)
\(=-\left(\frac{2}{5}y^2-3x^2\right)^2\)
\(\frac{12}{5}x^2y^2-9x^4-\frac{4}{25}y^4\)
\(=-\left(9x^4-\frac{12}{5}x^2y^2+\frac{4}{25}y^4\right)\)
\(=-\left[\left(3x\right)^2-2.3x^2.\frac{2}{5}y^2+\left(\frac{2}{5}y^2\right)^2\right]\)
\(=-\left(3x^2+\frac{2}{5}y^2\right)\)