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a)x6-y6+
=[(x2)3-(y2)3]+(x4+x2y2+y4)
=[(x2-y2)(x4+x2y2+y4)]+(x4+x2y2+y4)
=(x4+x2y2+y4)[(x2-y2)+1]
=(x2-xy+y2)(x2+xy+y2)(x2-y2+1)
Bài 2:
1: \(\left(2x-1\right)^2-4\left(2x-1\right)=0\)
=>\(\left(2x-1\right)\left(2x-1-4\right)=0\)
=>(2x-1)(2x-5)=0
=>\(\left[{}\begin{matrix}2x-1=0\\2x-5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=\dfrac{5}{2}\end{matrix}\right.\)
2: \(9x^3-x=0\)
=>\(x\left(9x^2-1\right)=0\)
=>x(3x-1)(3x+1)=0
=>\(\left[{}\begin{matrix}x=0\\3x-1=0\\3x+1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{1}{3}\\x=-\dfrac{1}{3}\end{matrix}\right.\)
3: \(\left(3-2x\right)^2-2\left(2x-3\right)=0\)
=>\(\left(2x-3\right)^2-2\left(2x-3\right)=0\)
=>(2x-3)(2x-3-2)=0
=>(2x-3)(2x-5)=0
=>\(\left[{}\begin{matrix}2x-3=0\\2x-5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=\dfrac{5}{2}\end{matrix}\right.\)
4: \(\left(2x-5\right)\left(x+5\right)-10x+25=0\)
=>\(2x^2+10x-5x-25-10x+25=0\)
=>\(2x^2-5x=0\)
=>\(x\left(2x-5\right)=0\)
=>\(\left[{}\begin{matrix}x=0\\2x-5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{5}{2}\end{matrix}\right.\)
Bài 1:
1: \(3x^3y^2-6xy\)
\(=3xy\cdot x^2y-3xy\cdot2\)
\(=3xy\left(x^2y-2\right)\)
2: \(\left(x-2y\right)\left(x+3y\right)-2\left(x-2y\right)\)
\(=\left(x-2y\right)\cdot\left(x+3y\right)-2\cdot\left(x-2y\right)\)
\(=\left(x-2y\right)\left(x+3y-2\right)\)
3: \(\left(3x-1\right)\left(x-2y\right)-5x\left(2y-x\right)\)
\(=\left(3x-1\right)\left(x-2y\right)+5x\left(x-2y\right)\)
\(=(x-2y)(3x-1+5x)\)
\(=\left(x-2y\right)\left(8x-1\right)\)
4: \(x^2-y^2-6y-9\)
\(=x^2-\left(y^2+6y+9\right)\)
\(=x^2-\left(y+3\right)^2\)
\(=\left(x-y-3\right)\left(x+y+3\right)\)
5: \(\left(3x-y\right)^2-4y^2\)
\(=\left(3x-y\right)^2-\left(2y\right)^2\)
\(=\left(3x-y-2y\right)\left(3x-y+2y\right)\)
\(=\left(3x-3y\right)\left(3x+y\right)\)
\(=3\left(x-y\right)\left(3x+y\right)\)
6: \(4x^2-9y^2-4x+1\)
\(=\left(4x^2-4x+1\right)-9y^2\)
\(=\left(2x-1\right)^2-\left(3y\right)^2\)
\(=\left(2x-1-3y\right)\left(2x-1+3y\right)\)
8: \(x^2y-xy^2-2x+2y\)
\(=xy\left(x-y\right)-2\left(x-y\right)\)
\(=\left(x-y\right)\left(xy-2\right)\)
9: \(x^2-y^2-2x+2y\)
\(=\left(x^2-y^2\right)-\left(2x-2y\right)\)
\(=\left(x-y\right)\left(x+y\right)-2\left(x-y\right)\)
\(=\left(x-y\right)\left(x+y-2\right)\)
\(=16-\left(x^2-2xy+y^2\right)\)
\(=4^2-\left(x-y\right)^2=\left(4-x+y\right)\left(4+x-y\right)\)
x11 + x10 + 1
= ( x11 - x9 + x8 - x6 + x5 - x3 + x2 ) + ( x10 - x8 + x7 - x5 + x4 - x2 + x ) + ( x9 - x7 + x6 - x4 + x3 - x + 1 )
= x2 ( x9 - x7 + x6 - x4 + x3 - x + 1 ) + x( ( x9 - x7 + x6 - x4 + x3 - x + 1 ) + 1( x9 - x7 + x6 - x4 + x3 - x + 1 )
= ( x2 + x + 1 ) ( x9 - x7 + x6 - x4 + x3 - x + 1 )
Chỗ nào không hiểu thì ib nhé :)
x11+x10+1
=x11+x10+x9-x9-x8-x7+x8+x7+x6-x6-x5-x4+x5+x4+x3-x3-x2-x+x2+x+1
=(x11+x10+x9)-(x9+x8+x7)+(x8+x7+x6)-(x6+x5+x4)+(x5+x4+x3)-(x3+x2+x)+(x2+x+1)
=x9(x2+x+1)-x7(x2+x+1)+x6(x2+x+1)-x4(x2+x+1)+x3(x2+x+1)-x(x2+x+1)+(x2+x+1)
=(x2+x+1)(x9-x7+x6-x4+x3-x+1)
A.(x+2y).(x+2y-1) = x^2 +4xy + 4y^2 - x - 2y
B. (x-2y).(x+2y-1) = x^2 - x - 4y^2 + 2y
C. (x-2y).(x-2y+1) = x^2 - 4xy + 4y^2 + x - 2y
D.(x+2y).(x-2y) = x^2 - 4y^2
=>....
25n(n-1)-50(n-1) luôn chia hết cho 150 với mọi n là số nguyên
giúp mình chứng minh nha . Cám ơn mấy bạn