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NL
1
4 tháng 8 2017
x2 - 25 + y2 + 2xy
x2 - 25 + y2 + 2xy
Chưa trả lờiNhật Linh Đặng
(2x + 1)2 - 49x2 + 56x - 1
x2 - 25 + y2 + 2xy
(2x + 1)2 - 49x2 + 56x - 16
xm + 4 - xm + 3 - x - 1
a3 + b3 + c3 - 3abc
x2 - 25 + y2 + 2xy
(2x + 1)2 - 49x2 + 56x - 16
xm + 4 - xm + 3 - x - 1
a3 + b3 + c3 - 3abc
x2 - 25 + y2 + 2xy
(2x + 1)2 - 49x2 + 56x - 16
xm + 4 - xm + 3 - x - 1
a3 + b3 + c3 - 3abc
x2 - 25 + y2 + 2xy
(2x + 1)2 - 49x2 + 56x - 16
xm + 4 - xm + 3 - x - 1
a3 + b3 + c3 - 3abc
x2 - 25 + y2 + 2xy
x2 - 25 + y2 + 2xy
(2x + 1)2 - 49x2 + 56x - 16
xm + 4 - xm + 3 - x - 1
a3 + b3 + c3 - 3abc
(2x + 1)2 - 49x2 + 56x -
x2 - 25 + y2 + 2xy
(2x + 1)2 - 49x2 + 56x - 16
xm + 4 - xm + 3 - x - 1
a3 + b3 + c3 - 3abc
16
xm + 4 - xm + 3 - x - 1
a3 + b3 + c3 - 3abc
6
xm + 4 - xm + 3 - x - 1
a3 + b3 + c3 - 3abc
(2x + 1)2 - 49x2 + 56x - 16
xm + 4 - xm + 3 - x - 1
a3 + b3 + c3 - 3abc
KK
27 tháng 10 2017
c) 49x2+14x+1=0
=>(7x+1)2=0
= > 7x+1=0
=> 7x=-1
=> x=-\(\dfrac{1}{7}\)
4 tháng 8 2018
a,49x2-1=0
\(\Leftrightarrow\left(7x\right)^2-1^2=0\)\(\Leftrightarrow\left(7x-1\right)\left(7x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}7x-1=0\\7x+1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}7x=1\\7x=-1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{7}\\x=\dfrac{-1}{7}\end{matrix}\right.\)
b,(2x-1)2-(4x+1)(x-3)= -3
\(\Leftrightarrow\left[\left(2x\right)^2-2x+1\right]-\left(4x^2-12x+x-3\right)=0\)
\(\Leftrightarrow4x^2-2x+1-4x^2+12x-x+3=0\)
\(\Leftrightarrow9x+4=0\Leftrightarrow9x=-4\Leftrightarrow x=\dfrac{-4}{9}\)
23 tháng 2 2020
a) Ta có: \(\left(2x+3\right)^2-\left(5+x\right)\left(2x+3\right)=0\)
\(\Leftrightarrow\left(2x+3\right)\left(2x+3+5+x\right)=0\)
\(\Leftrightarrow\left(2x+3\right)\left(3x+8\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}2x+3=0\\3x+8=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=-3\\3x=-8\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\frac{-3}{2}\\x=\frac{-8}{3}\end{matrix}\right.\)
Vậy: \(x\in\left\{\frac{-3}{2};\frac{-8}{3}\right\}\)
b) Ta có: \(\left(2x+5\right)^2-\left(2x-5\right)^2=6x+8\)
\(\Leftrightarrow\left(2x+5+2x-5\right)\left(2x+5-2x+5\right)-6x-8=0\)
\(\Leftrightarrow40x-6x-8=0\)
\(\Leftrightarrow34x=8\)
\(\Leftrightarrow x=\frac{8}{34}=\frac{4}{17}\)
Vậy: \(x=\frac{4}{17}\)
c) Ta có: \(\left(4x+3\right)^2=4\left(x-1\right)^2\)
\(\Leftrightarrow16x^2+24x+9=4\left(x^2-2x+1\right)\)
\(\Leftrightarrow16x^2+24x+9-4x^2+8x-4=0\)
\(\Leftrightarrow12x^2+32x+5=0\)
\(\Leftrightarrow12x^2+2x+30x+5=0\)
\(\Leftrightarrow2x\left(6x+1\right)+5\left(6x+1\right)=0\)
\(\Leftrightarrow\left(6x+1\right)\left(2x+5\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}6x+1=0\\2x+5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}6x=-1\\2x=-5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\frac{-1}{6}\\x=\frac{-5}{2}\end{matrix}\right.\)
Vậy: \(x\in\left\{\frac{-1}{6};\frac{-5}{2}\right\}\)
d) Ta có: \(\left(7x-1\right)\left(3x-2\right)-49x^2+14x=1\)
\(\Leftrightarrow\left(7x-1\right)\left(3x-2\right)-\left(49x^2-14x+1\right)=0\)
\(\Leftrightarrow\left(7x-1\right)\left(3x-2\right)-\left(7x-1\right)^2=0\)
\(\Leftrightarrow\left(7x-1\right)\left[3x-2-\left(7x-1\right)\right]=0\)
\(\Leftrightarrow\left(7x-1\right)\left(3x-2-7x+1\right)=0\)
\(\Leftrightarrow\left(7x-1\right)\left(-4x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}7x-1=0\\-4x-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}7x=1\\-4x=1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\frac{1}{7}\\x=\frac{-1}{4}\end{matrix}\right.\)
Vậy: \(x\in\left\{\frac{1}{7};\frac{-1}{4}\right\}\)
KN
30 tháng 9 2017
a) x2 - 2x - 4y2 - 4y
= (x2 - 4y2) - (2x + 4y)
= (x + 2y)(x - 2y) - 2(x + 2y)
= (x + 2y)(x - 2y - 2)
= (x + 2y)[x - 2(y + 1)]
b) x4 + 2x3 - 4x - 4
= (x4 - 4) + ( 2x3 - 4x)
= (x2 - 2)(x2 + 2) + 2x(x2 - 2)
= (x2 - 2)(x2 + 2 + 2x)
c) x3 + 2x2y - x -2y
= (x3 - x) + (2x2y - 2y)
= x(x2 - 1) + 2y(x2 - 1)
= (x + 2y)(x2 - 1)
12 tháng 10 2018
a) ( 3x -1 )2 - 16
= (3x -1 ) 2 - 42
= ( 3x -1 -4 ).( 3x -1 +4 )
b) ( 5x-4 ) 2 - 49x2
= ( 5x-4 ) 2 - (7x)2
=( 5x -4 -7x).( 5x -4 + 7x )
=( -2x -4 ) .( 12x -4 )
còn lại giống tương tự nha pạn
~ hok tốt ~
a) \(\left(2x+1\right)^2-49x^2+56x-16\)
\(=4x^2+4x+1-49x^2+56x-16\)
\(=-45x^2+60x-15\)
\(=-45x^2+45x+15x-15\)
\(=-45x\left(x-1\right)+15\left(x-1\right)\)
\(=\left(-45x+15\right)\left(x-1\right)\)
\(=-15\left(3x-1\right)\left(x-1\right).\)
câu b sai đề