phân tích đa thức sau thành nhân tử
a) a^2-a^2x-ay+xy
b)
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Bài 2 : Phân tích các đa thức sau thành nhân tử :
a) x2 - ( m + n )x + mn
b) ax + by + a - bx - ay - b
\(a,=x^2-mx-nx+mn=x\left(x-m\right)-n\left(x-m\right)=\left(x-n\right)\left(x-m\right)\\ b,=a\left(x-y\right)-b\left(x-y\right)+\left(a-b\right)\\ =\left(x-y\right)\left(a-b\right)+\left(a-b\right)=\left(a-b\right)\left(x-y+1\right)\)
b: \(=a\left(x-y\right)-b\left(x-y\right)+a-b\)
\(=\left(x-y+1\right)\left(a-b\right)\)
\(ax^2+a-axy+2ax-ay\)
\(a\left(x^2+2x+1\right)-ay\left(x+1\right)\)
\(a\left(x+1\right)^2-ay\left(x+1\right)\)
\(\left(x+1\right)\left[a\left(x+1\right)-ay\right]\)
\(\left(x+1\right)\left(ax+a-ay\right)\)
\(a\left(x+1\right)\left(x+1-y\right)\)
a)\(2x^2-12x=-18\)
\(\Leftrightarrow2x^2-12x+18=0\)
\(\Leftrightarrow2\left(x^2-6x+9\right)=0\)
\(\Leftrightarrow2\left(x-3\right)^2=0\)
\(\Leftrightarrow\left(x-3\right)^2=0\)
\(\Leftrightarrow x-3=0\)
\(\Leftrightarrow x=3\)
b) \(\left(4x^2-4x+1\right)-x^2=0\)
\(\Leftrightarrow\left(2x-1\right)^2-x^2=0\)
\(\Leftrightarrow\left(2x-1-x\right)\left(2x-1+x\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(3x-1\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x-1=0\\3x-1=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=1\\x=\frac{1}{3}\end{cases}}}\)
_Minh ngụy_
\(x^2-ay-y^2-ax\)
\(=\left(x^2-y^2\right)-\left(ax+ay\right)\)
\(=\left(x-y\right)\left(x+y\right)-a\left(x+y\right)\)
\(=\left(x+y\right)\left(x-y-a\right)\)
_Minh ngụy_
Bài 4:
Ta có: \(\left(x^3-x^2\right)-4x^2+8x-4=0\)
\(\Leftrightarrow x^2\left(x-1\right)-4\left(x-1\right)^2=0\)
\(\Leftrightarrow\left(x-1\right)\left(x-2\right)^2=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=2\end{matrix}\right.\)
a: \(\left(xy+ab\right)^2+\left(bx-ay\right)^2\)
\(=x^2y^2+a^2b^2+x^2b^2+a^2y^2\)
\(=x^2\left(b^2+y^2\right)+a^2\left(b^2+y^2\right)\)
\(=\left(b^2+y^2\right)\left(x^2+a^2\right)\)
\(a,2x^3y-2xy=2xy\left(x^2-1\right)=2xy\left(x-1\right)\left(x+1\right)\)
\(b,x^2-2x-4x^2-4x=-3x^2-2x-4x\\ =-3x^2-6x=-3\left(x^2+2x\right)=-3x\left(x+2\right)\)
a: \(=a\left(y^2-2yz+z^2\right)\)
\(=a\left(y-z\right)^2\)
b: \(=\left(x^2+6xy+9y^2\right)-16\)
=(x+3y)^2-16
=(x+3y+4)(x+3y-4)
c: \(=7\left(a-b\right)+\left(a-b\right)\left(a+b\right)\)
=(a-b)(7+a+b)
d: \(36x^4-13x^2\)
=x^2*36x^2-x^2*13
=x^2(36x^2-13)
f: x^2-2xy+y^2-49
=(x-y)^2-49
=(x-y-7)(x-y+7)
e: 2x^3-18x
=2x(x^2-9)
=2x(x-3)(x+3)
g: 2x+2y-x^2-xy
=2(x+y)-x(x+y)
=(x+y)(2-x)
h: (x^2+3)^2+16
=x^4+6x^2+25
=x^4+10x^2+25-4x^2
=(x^2+5)^2-4x^2
=(x^2-2x+5)(x^2+2x+5)