Phân tích đa thức thành nhân tử
\(ab^2-3a+b^2-3ab-3\)
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\(a^3-b^3+3a^2+3ab+b^2\)
\(=\left(a-b\right)\left(a^2+ab+b^2\right)+3\left(a^2+ab+b^2\right)\)
\(=\left(a-b+3\right)\left(a^2+ab+b^2\right)\)
a) Ta có: \(a^2-b^2-5a+5b\)
\(=\left(a-b\right)\left(a+b\right)-5\left(a-b\right)\)
\(=\left(a-b\right)\left(a+b-5\right)\)
b) Ta có: \(a^2-b^2-3ab^2-3a^2b\)
\(=\left(a-b\right)\left(a+b\right)-3ab\left(a+b\right)\)
\(=\left(a+b\right)\left(a-b-3ab\right)\)
\(1,\\ a,=4\left(x-2\right)^2+y\left(x-2\right)=\left(4x-8+y\right)\left(x-2\right)\\ b,=3a^2\left(x-y\right)+ab\left(x-y\right)=a\left(3a+b\right)\left(x-y\right)\\ 2,\\ a,=\left(x-y\right)\left[x\left(x-y\right)^2-y-y^2\right]\\ =\left(x-y\right)\left(x^3-2x^2y+xy^2-y-y^2\right)\\ b,=2ax^2\left(x+3\right)+6a\left(x+3\right)\\ =2a\left(x^2+3\right)\left(x+3\right)\\ 3,\\ a,=xy\left(x-y\right)-3\left(x-y\right)=\left(xy-3\right)\left(x-y\right)\\ b,Sửa:3ax^2+3bx^2+ax+bx+5a+5b\\ =3x^2\left(a+b\right)+x\left(a+b\right)+5\left(a+b\right)\\ =\left(3x^2+x+5\right)\left(a+b\right)\\ 4,\\ A=\left(b+3\right)\left(a-b\right)\\ A=\left(1997+3\right)\left(2003-1997\right)=2000\cdot6=12000\\ 5,\\ a,\Leftrightarrow\left(x-2017\right)\left(8x-2\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=2017\\x=\dfrac{1}{4}\end{matrix}\right.\\ b,\Leftrightarrow\left(x-1\right)\left(x^2-16\right)=0\Leftrightarrow\left[{}\begin{matrix}x=1\\x=4\\x=-4\end{matrix}\right.\)
\(\left(a+b\right)^3-3ab.\left(a+b\right)=\left(a+b\right)\left[\left(a+b\right)^2-3ab\right]=\left(a+b\right)\left(a^2+b^2-ab\right)\)
`(a+b)^3-3ab(a+b)`
`=(a+b)(a+b)^2-3ab(a+b)`
`=(a+b)[(a+b)^2-3ab]`
`=(a+b)(a^2+2ab+b^2-3ab)`
`=(a+b)(a^2-ab+b^2)`
2, a^3-3ab^2 = 5
<=> (a^3-3ab^2)^2 = 25
<=> a^6-6a^4b^2+9a^2b^4 = 25
b^3-3a^2b=10
<=> (b^3-3a^2b)^2 = 100
<=> b^6-6a^2b^4+9a^4b^2 = 100
=> 100+25 = a^6-6a^4b^2+9a^2b^4+b^6+6a^2b^4+9a^4b^2
<=> 125 = a^6+3a^4b^2+3a^3b^4+b^6 = (a^2+b^2)^3
<=> a^2+b^2 = 5
Khi đó : S = 2016.(a^2+b^2) = 2016.5 = 10080
Tk mk nha
1) \(x^2+6xy+5y^2-5y-x=\left(x^2+xy-x\right)+\left(5xy+5y^2-5y\right)\)
\(=x\left(x+y-1\right)+5y\left(x+y-1\right)\)
\(=\left(x+5y\right)\left(x+y-1\right)\)
2) Ta có : \(a^3-3ab^2-5\Rightarrow\left(a^3-3ab^2\right)^2=25\Rightarrow a^6-6a^4b^2+9a^2b^4=25\)
và \(b^3-3a^2b=10\Rightarrow\left(b^3-3a^2b\right)^2=100\Rightarrow b^6-6b^4a^2+9a^4b^2=100\)
\(\Rightarrow\)\(125=a^6+b^6+3a^2b^4+3a^4b^2\)
Hay \(125=\left(a^2+b^2\right)^2\Rightarrow a^2+b^2=5\)
Nên \(S=2016\left(a^2+b^2\right)=2016.5=10080\)
Ta có:A= 3a+3b-a^2-ab
=>A= (3a-a^2)+(3b-ab)
=>A= a(3-a)+b(3-a)
=>A= (a+b)(3-a)