\(^{x^2+5x-1=0}\)
tìm x
a)(5x-1)^2-5x(5x-1)=0
b)x(x+1)(x+2)=0
c)(3x+2)x-3(3x+2)=0
a/ \(\left(5x-1\right)^2-5x\left(5x-1\right)=0\)
\(\Leftrightarrow\left(5x-1\right)\left(5x-1-5x\right)=0\Leftrightarrow1-5x=0\Leftrightarrow x=\dfrac{1}{5}\)
Vaayj........
b/ \(x\left(x+1\right)\left(x+2\right)=0\Leftrightarrow\left[{}\begin{matrix}x=0\\x+1=0\Leftrightarrow x=-1\\x+2=0\Leftrightarrow x=-2\end{matrix}\right.\)
Vay......
c/ \(\left(3x+2\right)x-3\left(3x+2\right)=0\)
\(\Leftrightarrow\left(3x+2\right)\left(x-3\right)=0\Leftrightarrow\left[{}\begin{matrix}3x+2=0\\x-3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{2}{3}\\x=3\end{matrix}\right.\)
Vậy.....
tìm x
a)(5x-1)^2-5x(5x-1)=0
b)x(x+1)(x+2)=0
c)(3x+2)x-3(3x+2)=0
\(a)\) \(\left(5x-1\right)^2-5x\left(5x-1\right)=0\)
\(\Leftrightarrow\)\(\left(5x-1\right)\left(5x-1-5x\right)=0\)
\(\Leftrightarrow\)\(\left(5x-1\right).\left(-1\right)=0\)
\(\Leftrightarrow\)\(5x-1=0\)
\(\Leftrightarrow\)\(5x=1\)
\(\Leftrightarrow\)\(x=\frac{1}{5}\)
Vậy \(x=\frac{1}{5}\)
\(b)\) \(x\left(x+1\right)\left(x+2\right)=0\)
Suy ra \(x=0\) hoặc \(x+1=0\) hoặc \(x+2=0\)
\(\Leftrightarrow\)\(x=0\) hoặc \(x=-1\) hoặc \(x=-2\)
Vậy \(x=0\) hoặc \(x=-1\) hoặc \(x=-2\)
\(c)\) \(\left(3x+2\right)x-3\left(3x+2\right)=0\)
\(\Leftrightarrow\)\(\left(3x+2\right)\left(x-3\right)=0\)
\(\Leftrightarrow\)\(\orbr{\begin{cases}3x+2=0\\x-3=0\end{cases}\Leftrightarrow\orbr{\begin{cases}3x=0-2\\x=0+3\end{cases}}}\)
\(\Leftrightarrow\)\(\orbr{\begin{cases}3x=-2\\x=3\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{-2}{3}\\x=3\end{cases}}}\)
Vậy \(x=\frac{-2}{3}\) hoặc \(x=3\)
Chúc bạn học tốt ~
a/ \(\left(5x-1\right)^2-5x\left(5x-1\right)=0\)
<=> \(\left(5x-1\right)\left(5x-1-5x\right)=0\)
<=> \(-1\left(5x-1\right)=0\)
<=> \(5x-1=0\)
<=> \(5x=1\)
<=> \(x=\frac{1}{5}\)
b/ \(x\left(x+1\right)\left(x+2\right)=0\)
<=> \(x=0\) hoặc \(\orbr{\begin{cases}x+1=0\\x+2=0\end{cases}}\)
<=> \(x=0\)hoặc \(\orbr{\begin{cases}x=-1\\x=-2\end{cases}}\)
c/ \(\left(3x+2\right)x-3\left(3x+2\right)=0\)
<=> \(\left(3x+2\right)\left(x-3\right)=0\)
<=> \(\orbr{\begin{cases}3x+2=0\\x-3=0\end{cases}}\)
<=> \(\orbr{\begin{cases}3x=-2\\x=3\end{cases}}\)
<=> \(\orbr{\begin{cases}x=-\frac{2}{3}\\x=3\end{cases}}\)
a. 4x(x+1)-5(x+1)=0
b. 5x(x-20)+5x-100=0
c. 2(x-2)+(x-2)^2=0
d. (x-3)^2-5x-x^2=12
a, \(4x\left(x+1\right)-5\left(x+1\right)=0\)
\(\left(x+1\right)\left(4x-5\right)\)=0
\(\left\{{}\begin{matrix}x+1=0\\4x-5=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=\left(-1\right)\\4x=5\Rightarrow x=\frac{5}{4}\end{matrix}\right.\)
b, \(5x\left(x-20\right)+5x-100=0\)
\(5x\left(x-20\right)+\left(5x-100\right)=0\)
\(5x\left(x-20\right)+5\left(x-20\right)=0\)
\(\left(x-20\right)\left(5x+5\right)\)= 0
\(\left\{{}\begin{matrix}x-20=0\\5x+5=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=20\\5x=-5\Rightarrow x=-1\end{matrix}\right.\)
c, \(2\left(x-2\right)+\left(x-2\right)^2=0\)
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Nghiệm
Lời giải thu được
Vậy x= 0 và x = 2
d, \(\left(x-3\right)^2-5x-x^2=12\)
\(\left(x^2-2.x.3+3^2\right)-5x-x^2=12\)
\(x^2-6x+9-5x-x^2=12\)
\(-11x+9=12\)
\(-11x=3\)
=> \(x=-\frac{3}{11}\)
Giai phường trình sau:
a, \(3x^2+2x-1=0\) e, \(4x^2-12x+5=0\) i,\(2x^2+5x-3=0\)
b,\(x^2-5x+6=0\) f, \(2x^2+5x+3=0\) j,\(x^2+6x-16=0\)
c,\(x^2-3x+2=0\) g,\(x^2+x-2=0\)
d,\(2x^2-6x+1=0\) h, \(x^2-4x+3=0\)
a) Ta có: \(3x^2+2x-1=0\)
\(\Leftrightarrow3x^2+3x-x-1=0\)
\(\Leftrightarrow3x\left(x+1\right)-\left(x+1\right)=0\)
\(\Leftrightarrow\left(x+1\right)\left(3x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x+1=0\\3x-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-1\\3x=1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-1\\x=\dfrac{1}{3}\end{matrix}\right.\)
Vậy: \(S=\left\{-1;\dfrac{1}{3}\right\}\)
b) Ta có: \(x^2-5x+6=0\)
\(\Leftrightarrow x^2-2x-3x+6=0\)
\(\Leftrightarrow x\left(x-2\right)-3\left(x-2\right)=0\)
\(\Leftrightarrow\left(x-2\right)\left(x-3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-2=0\\x-3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=3\end{matrix}\right.\)
Vậy: S={2;3}
c) Ta có: \(x^2-3x+2=0\)
\(\Leftrightarrow x^2-x-2x+2=0\)
\(\Leftrightarrow x\left(x-1\right)-2\left(x-1\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(x-2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-1=0\\x-2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=2\end{matrix}\right.\)
Vậy: S={1;2}
d) Ta có: \(2x^2-6x+1=0\)
\(\Leftrightarrow2\left(x^2-3x+\dfrac{1}{3}\right)=0\)
mà \(2\ne0\)
nên \(x^2-3x+\dfrac{1}{3}=0\)
\(\Leftrightarrow x^2-2\cdot x\cdot\dfrac{3}{2}+\dfrac{9}{4}-\dfrac{23}{12}=0\)
\(\Leftrightarrow\left(x-\dfrac{3}{2}\right)^2=\dfrac{23}{12}\)
\(\Leftrightarrow\left[{}\begin{matrix}x-\dfrac{3}{2}=\dfrac{\sqrt{69}}{6}\\x-\dfrac{3}{2}=\dfrac{-\sqrt{69}}{6}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{9+\sqrt{69}}{6}\\x=\dfrac{9-\sqrt{69}}{6}\end{matrix}\right.\)
Vậy: \(S=\left\{\dfrac{9+\sqrt{69}}{6};\dfrac{9-\sqrt{69}}{6}\right\}\)
e) Ta có: \(4x^2-12x+5=0\)
\(\Leftrightarrow4x^2-10x-2x+5=0\)
\(\Leftrightarrow2x\left(2x-5\right)-\left(2x-5\right)=0\)
\(\Leftrightarrow\left(2x-5\right)\left(2x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-5=0\\2x-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=5\\2x=1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{2}\\x=\dfrac{1}{2}\end{matrix}\right.\)
Vậy: \(S=\left\{\dfrac{5}{2};\dfrac{1}{2}\right\}\)
Tìm x
a) 4x(x + 1) = 8(x + 1)
b) x(x – 1) – 2(1 – x) = 0
c) 5x(x – 2) – (2 – x) = 0
d) 5x(x – 200) – x + 200 = 0
e) x3 + 4x = 0
f) (x + 1) = (x + 1)2
a) 4x(x+1)=8(x+1)
<=>4x(x+1)-8(x+1)=0
<=>(4x-8)(x+1)=0
<=>\(\left[\begin{array}{} 4x-8=0\\ x+1=0 \end{array} \right.\)
<=>\(\left[\begin{array}{} x=2\\ x=-1 \end{array} \right.\)
Vậy...
b)x(x-1)-2(1-x)=0
<=>(x+2)(x-1)=0
<=>\(\left[\begin{array}{} x+2=0\\ x-1=0 \end{array} \right.\)
<=>\(\left[\begin{array}{} x=-2\\ x=1 \end{array} \right.\)
Vậy...
c)5x(x-2)-(2-x)=0
<=>(5x+1)(x-2)=0
<=>\(\left[\begin{array}{} 5x+1=0\\ x-2 \end{array} \right.\)
<=>\(\left[\begin{array}{} x=-1/5\\ x=2 \end{array} \right.\)
d)5x(x-200)-x+200=0
<=>(5x-1)(x-200)=0
<=>\(\left[\begin{array}{} 5x-1=0\\ x-200=0 \end{array} \right.\)
<=>\(\left[\begin{array}{} x=1/5\\ x=200 \end{array} \right.\)
e)\(x^3+4x=0 \)
\(\Leftrightarrow x(x^2+4)=0 \)
\(\Leftrightarrow \left[\begin{array}{} x=0\\ x^2+4=0 (loại vì x^2+4>=0 với mọi x) \end{array} \right.\)
Vậy x=0
f)\((x+1)=(x+1)^2\)
\(\Leftrightarrow (x+1)-(x+1)^2=0\)
\(\Leftrightarrow (x+1)(1-x-1)=0\)
\(\Leftrightarrow (x+1)(-x)=0\)
\(\Leftrightarrow \left[\begin{array}{} x=-1\\ x=0 \end{array} \right.\)
Vậy....
Đề: Tìm x
a)2x.(3x+5)-x.(6x-1)=33 k)5(x+3)-2x(x+3)=0
b)x(3x-1)+12x-4=0 i)5x(x-2)-(2-x)=0
c)5x(2x+1)-12x-6=0 m)x(x-1)-2(1-x)=0
d)x3-5x2+4x-20=0
e)2x3-5x2+2x-5=0
g)(x-2)3-x(x+1).(x-1)+62=5
a)2x.(3x+5)-x.(6x-1)=33
=>\(6x^2+10x-6x^2+x=33\)
=>11x=33
=>x=3
b)x(3x-1)+12x-4=0
=>x(3x-1)+4(3x-1)=0
=>(x-4)(3x-1)=0
=>x-4=0 hoặc 3x-1=0
+)x-4=0 +)3x-1=0
=>x=4 =>x=\(\frac{1}{3}\)
c)5x(2x+1)-12x-6=0
=>10x\(^2\)+5x-12x-6=0
=>10x\(^2\)-7x-6=0
=>(10x\(^2\)+5x)-(12x+6)=0
=>5x(2x+1)-6(2x+1)=0
=>(5x-6)(2x+1)=0
=>\(\left[{}\begin{matrix}5x-6=0\\2x+1=0\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}x=\frac{6}{5}\\x=\frac{-1}{2}\end{matrix}\right.\)
Bài 2 :Tim x biết 1)16x^2 - 9(x + 1)^2 = 0 2) (5x - 4)^2 - 49x^2 = 0 3) 5x^3 - 20x = 0
a, \(16x^2-9\left(x+1\right)^2=0\)
\(\Leftrightarrow\left(4x\right)^2-\left(3x+3\right)^2=0\Leftrightarrow\left(4x-3x-3\right)\left(4x+2x+3\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left(6x+3\right)=0\Leftrightarrow x=-\frac{1}{2};x=3\)
b, \(\left(5x-4\right)^2-49x^2=0\Leftrightarrow\left(5x-4-7x\right)\left(5x-4+7x\right)=0\)
\(\Leftrightarrow\left(-2x-4\right)\left(12x-4\right)=0\Leftrightarrow x=-2;x=\frac{1}{3}\)
c, \(5x^3-20x=0\Leftrightarrow5x\left(x^2-4\right)=0\)
\(\Leftrightarrow5x\left(x-2\right)\left(x+2\right)=0\Leftrightarrow x=0;x=\pm2\)
Bài 2 :Tim x biết 1)16x^2 - 9(x + 1)^2 = 0 2) (5x - 4)^2 - 49x^2 = 0 3) 5x^3 - 20x = 0
1: Ta có: \(16x^2-9\left(x+1\right)^2=0\)
\(\Leftrightarrow\left(4x-3x-3\right)\left(4x+3x+3\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left(7x+3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-\dfrac{7}{3}\end{matrix}\right.\)
2: Ta có: \(\left(5x-4\right)^2-49x^2=0\)
\(\Leftrightarrow\left(5x-4-7x\right)\left(5x-4+7x\right)=0\)
\(\Leftrightarrow\left(2x+4\right)\left(12x-4\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=\dfrac{1}{3}\end{matrix}\right.\)
3: Ta có: \(5x^3-20x=0\)
\(\Leftrightarrow5x\left(x-2\right)\left(x+2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=2\\x=-2\end{matrix}\right.\)
Tìm x:
a) 5x(x-1)=x-1
b) 2(x+5)-x2-5x=0
c) x2-2x-3=0
d) 2x2+5x-3=0
a) 5x( x - 1 ) = x - 1
<=> 5x2 - 5x = x - 1
<=> 5x2 - 5x - x + 1 = 0
<=> 5x2 - 6x + 1 = 0
<=> 5x2 - 5x - x + 1 = 0
<=> 5x( x - 1 ) - 1( x - 1 ) = 0
<=> ( x - 1 )( 5x - 1 ) = 0
<=> \(\orbr{\begin{cases}x-1=0\\5x-1=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=1\\x=\frac{1}{5}\end{cases}}\)
b) 2( x + 5 ) - x2 - 5x = 0
<=> 2x + 10 - x2 - 5x = 0
<=> -x2 - 3x + 10 = 0
<=> -x2 - 5x + 2x + 10 = 0
<=> -x( x + 5 ) + 2( x + 5 ) = 0
<=> ( x + 5 )( 2 - x ) = 0
<=> \(\orbr{\begin{cases}x+5=0\\2-x=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=-5\\x=2\end{cases}}\)
c) x2 - 2x - 3 = 0
<=> x2 + x - 3x - 3 = 0
<=> x( x + 1 ) - 3( x + 1 ) = 0
<=> ( x + 1 )( x - 3 ) = 0
<=> \(\orbr{\begin{cases}x+1=0\\x-3=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=-1\\x=3\end{cases}}\)
d) 2x2 + 5x - 3 = 0
<=> 2x2 - x + 6x - 3 = 0
,<=> x( 2x - 1 ) + 3( 2x - 1 ) = 0
<=> ( 2x - 1 )( x + 3 ) = 0
<=> \(\orbr{\begin{cases}2x-1=0\\x+3=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=\frac{1}{2}\\x=-3\end{cases}}\)
a) 5x ( x - 1 ) = x - 1 <=> 5x2 - 5x - x + 1 = 0
<=> 5x2 - 6x + 1 = 0 <=> 5x2 - x - ( 5x - 1 ) = 0
<=> x ( 5x - 1 ) - ( 5x - 1 ) = 0 <=> ( x - 1 )( 5x - 1 ) = 0
<=> x = 1 hoặc x = 1/5
b) 2 ( x + 5 ) - x2 - 5x = 0 <=> 2 ( x + 5 ) - x ( x + 5 ) = 0
<=> ( 2 - x ) ( x + 5 ) = 0 <=> x = 2 hoặc x = -5
c) x2 - 2x - 3 = 0 <=> x2 + x - 3x - 3 = 0
<=> x ( x + 1 ) - 3 ( x + 1 ) = 0 <=> ( x - 3 ) ( x + 1 ) = 0
<=> x = 3 hoặc x = -1
d) 2x2 + 5x - 3 = 0
Ta có : delta = 52 - 4.2.3 = 25 - 24 = 1
Khi đó : x = -1 hoặc x = 3/2
a) 5x(x-1)=x-1
\(\Leftrightarrow\)5x(x-1)-(x-1)=0
\(\Leftrightarrow\)(x-1)(5x-1)=0
\(\Leftrightarrow\)\(\orbr{\begin{cases}x-1=0\\5x-1=0\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=1\\x=\frac{1}{5}\end{cases}}\)
vậy x=1 hoặc x=1/5
b) 2(x+5)-x2-5x=0
\(\Leftrightarrow2\left(x+5\right)-x\left(x+5\right)=0\)
\(\Leftrightarrow\left(x+5\right)\left(2-x\right)\)=0
\(\Leftrightarrow\orbr{\begin{cases}x+5=0\\2-x=0\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=-5\\x=2\end{cases}}\)
Vậy x=2 hoặc x=-5
c) x2-2x-3=0
\(\Leftrightarrow x^2-3x+x-3=0\)\(\Leftrightarrow x\left(x-3\right)+\left(x-3\right)=0\)\(\Leftrightarrow\left(x-3\right)\left(x+1\right)=0\)\(\Leftrightarrow\orbr{\begin{cases}x-3=0\\x+1=0\end{cases}}\)\(\Leftrightarrow\orbr{\begin{cases}x=3\\x=-1\end{cases}}\)
vậy...