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giúp mik gấp vs mng. Làm hết hộ mik ạ. Mik cảm ơn
3
25 tháng 8 2021
18, \(\frac{x}{2}+\frac{x^2}{8}=0\Leftrightarrow4x+x^2=0\Leftrightarrow x\left(x+4\right)=0\Leftrightarrow x=-4;x=0\)
19, \(4-x=2\left(x-4\right)^2\Leftrightarrow\left(4-x\right)-2\left(4-x\right)^2=0\)
\(\Leftrightarrow\left(4-x\right)\left[1-2\left(4-x\right)\right]=0\Leftrightarrow\left(4-x\right)\left(-7+2x\right)=0\Leftrightarrow x=4;x=\frac{7}{2}\)
20, \(\left(x^2+1\right)\left(x-2\right)+2x-4=0\Leftrightarrow\left(x^2+1\right)\left(x-2\right)+2\left(x-2\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(x^2+3>0\right)=0\Leftrightarrow x=2\)
25 tháng 8 2021
21, \(x^4-16x^2=0\Leftrightarrow x^2\left(x-4\right)\left(x+4\right)=0\Leftrightarrow x=0;x=\pm4\)
22, \(\left(x-5\right)^3-x+5=0\Leftrightarrow\left(x-5\right)^3-\left(x-5\right)=0\)
\(\Leftrightarrow\left(x-5\right)\left[\left(x-5\right)^2-1\right]=0\Leftrightarrow\left(x-5\right)\left(x-6\right)\left(x-4\right)=0\Leftrightarrow x=4;x=5;x=6\)
23, \(5\left(x-2\right)-x^2+4=0\Leftrightarrow5\left(x-2\right)-\left(x-2\right)\left(x+2\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(5-x-2\right)=0\Leftrightarrow x=2;x=3\)
NN
Mọi Người giải giúp em ạ em cảm ơn ạ
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TT
25 tháng 10 2017
Đề số 3.
1.
a,\(4x\left(5x^2-2x+3\right)\)
\(=20x^3-8x^2+12x\)
b.\(\left(x-2\right)\left(x^2-3x+5\right)\)
\(=x^3-3x^2+5x-2x^2+6x-10\)
\(=x^3-5x^2+11x-10\)
c,\(\left(10x^4-5x^3+3x^2\right):5x^2\)
\(=2x^2-x+\dfrac{3}{5}\)
d,\(\left(x^2-12xy+36y^2\right):\left(x-6y\right)\)
\(=\left(x-6y\right)^2:\left(x-6y\right)\)
\(=x-6y\)
2.
a,\(x^2+5x+5xy+25y\)
\(=\left(x^2+5x\right)+\left(5xy+25y\right)\)
\(=x\left(x+5\right)+5y\left(x+5\right)\)
\(=\left(x+5y\right)\left(x+5\right)\)
b,\(x^2-y^2+14x+49\)
\(=\left(x^2+14x+49\right)-y^2\)
\(=\left(x+7\right)^2-y^2\)
\(=\left(x+7-y\right)\left(x+7+y\right)\)
c,\(x^2-24x-25\)
\(=x^2+25x-x-25\)
\(=\left(x^2-x\right)+\left(25x-25\right)\)
\(=x\left(x-1\right)+25\left(x-1\right)\)
\(=\left(x+25\right)\left(x-1\right)\)
3.
a,\(5x\left(x-3\right)-x+3=0\)
\(5x\left(x-3\right)-\left(x-3\right)=0\)
\(\left(5x-1\right)\left(x-3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}5x-1=0\\x-3=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}5x=1\\x=3\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{5}\\x=3\end{matrix}\right.\)
Vậy \(x=\dfrac{1}{5}\) hoặc \(x=3\)
b.\(3x\left(x-5\right)-\left(x-1\right)\left(2+3x\right)=30\)
\(3x^2-15x-\left(2x+3x^2-2-3x\right)=30\)
\(3x^2-15x-2x-3x^2+2+3x=30\)
\(-14x+2=30\)
\(-14x=28\)
\(x=-2\)
c,\(\left(x+2\right)\left(x+3\right)-\left(x-2\right)\left(x+5\right)=0\)
\(x^2+3x+2x+6-\left(x^2+5x-2x-10\right)=0\)
\(x^2+5x+6-x^2-5x+2x+10=0\)
\(2x+16=0\)
\(2x=-16\)
\(x=-8\)
Mình học chật hình không giúp bạn được.Xin lỗi!
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áp dụng bài hc sẽ ra
mờ quá
Trả lời:
a, ax - ay + bx - by = ( ax - ay ) + ( bx - by ) = a ( x - y ) + b ( x - y ) = ( x - y )( a + b )
b, ax - ay + bx - by (trùng ý a)
c, x2 + xy + ax + ay = ( x2 + xy ) + ( ax + ay ) = x ( x + y ) + a ( x + y ) = ( x + y )( x + a )
d, x2y + xy2 - x - y = ( x2y - x ) + ( xy2 - y ) = x ( xy - 1 ) + y ( xy - 1 ) = ( xy - 1 )( x + y )
e, x2y - xy2 - 5x + 5y = ( x2y - xy2 ) - ( 5x - 5y ) = xy ( x - y ) - 5 ( x - y ) = ( x - y )( xy - 5 )
f, 2x2 + 2xy - x - y = ( 2x2 + 2xy ) - ( x + y ) = 2x ( x + y ) - ( x + y ) = ( x + y )( 2x - 1 )
g, x2y - 4x + xy2 - 4y = ( x2y - 4x ) + ( xy2 - 4y ) = x ( xy - 4 ) + y ( xy - 4 ) = ( xy - 4 )( x + y )
h, x4 + x3 + x + 1 = ( x4 + x3 ) + ( x + 1 ) = x3 ( x + 1 ) + ( x + 1 ) = ( x + 1 )( x3 + 1 ) = ( x + 1 )( x + 1 )( x2 - x + 1 ) = ( x + 1 )2( x2 - x + 1)
i, x4 - x3 - x + 1 = ( x4 - x3 ) - ( x - 1 ) = x3 ( x - 1 ) - ( x - 1 ) = ( x - 1 )( x3 - 1 ) = ( x - 1 )( x - 1 )( x2 + x + 1 ) = ( x - 1 )2( x2 + x + 1 )
j, x2 + x - y2 + y = ( x2 - y2 ) + ( x + y ) = ( x + y ) ( x - y ) + ( x + y ) = ( x + y )( x - y + 1 )
k, 4x2 - 9y2 + 4x - 6y = ( 4x2 - 9y2 ) + ( 4x - 6y ) = ( 2x - 3y ) ( 2x + 3y ) + 2 ( 2x - 3y ) = ( 2x - 3y )( 2x + 3y + 2 )
l, x2 + x + 2xy + y + y2 = ( x2 + 2xy + y2 ) + ( x + y ) = ( x + y )2 + ( x + y ) = ( x + y )( x + y + 1 )
m, 16x2 - 9 - 24xy + 9y2 = ( 16x2 - 24xy + 9y2 ) - 9 = ( 4x - 3y )2 - 32 = ( 4x - 3y - 3 )( 4x - 3y + 3 )
n, 4x2 - 4xy - 1 + y2 = ( 4x2 - 4xy + y2 ) - 1 = ( 2x - y ) - 1 = ( 2x - y - 1 )( 2x - y + 1 )
o, Sửa đề: x2 - x - 2xy + y + y2 = ( x2 - 2xy + y2 ) - ( x - y ) = ( x - y )2 - ( x - y ) = ( x - y )( x - y - 1 )
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