Tìm x, biết : 2x² - 3x = 0
Tìm x biết:
\(a) x^2+3x-10=0 \)
\(b) x^2-5x-6=0\)
\(c) 2x^2+3x-2=0\)
a: Ta có: \(x^2+3x-10=0\)
\(\Leftrightarrow\left(x+5\right)\left(x-2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-5\\x=2\end{matrix}\right.\)
b: Ta có: \(x^2-5x-6=0\)
\(\Leftrightarrow\left(x-6\right)\left(x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=6\\x=-1\end{matrix}\right.\)
x2( x + 1 ) + 2x( x + 1 ) = 0 <=> x( x + 1 )( x + 2 ) = 0 <=> x = 0 hoặc x = -1 hoặc x = -2
x( 3x - 1 ) - 5( 1 - 3x ) = 0 <=> x( 3x - 1 ) + 5( 3x - 1 ) = 0 <=> ( 3x - 1 )( x + 5 ) = 0 <=> x = 1/3 hoặc x = -5
Trả lời:
1, \(x^2\left(x+1\right)+2x\left(x+1\right)=0\)
\(\Leftrightarrow x\left(x+1\right)\left(x+2\right)=0\)
\(\Leftrightarrow x=0;x=-1;x=-2\)
Vậy x = 0; x = - 1; x = - 2 là nghiệm của pt.
2, \(x\left(3x-1\right)-5\left(1-3x\right)=0\)
\(\Leftrightarrow x\left(3x-1\right)+5\left(3x-1\right)=0\)
\(\Leftrightarrow\left(3x-1\right)\left(x+5\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}3x-1=0\\x+5=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{1}{3}\\x=-5\end{cases}}}\)
Vậy x = 1/3; x = - 5 là nghiệm của pt.
tìm x biết
a/x^3+3x^2+3x+2=0
b/x^4-2x^3+2x-1=0
c/x^4-3x^3-6x^2+8x=0
a) \(x^3+3x^2+3x+2=0\)
<=> \(x^3+x^2+x+2x^2+2x+2=0\)
<=> \(x\left(x^2+x+1\right)+2\left(x^2+x+1\right)=0\)
<=> \(\left(x+2\right)\left(x^2+x+1\right)=0\)
tự làm
b) \(x^4-2x^3+2x-1=0\)
<=> \(\left(x^4-3x^3+3x^2-x\right)+\left(x^3-3x^2+3x-1\right)=0\)
<=> \(x\left(x^3-3x^2+3x-1\right)+\left(x^3-3x^2+3x-1\right)=0\)
<=> \(\left(x^3-3x^2+3x-1\right)\left(x+1\right)=0\)
<=> \(\left(x-1\right)^3\left(x+1\right)=0\)
tự làm
c) \(x^4-3x^3-6x^2+8x=0\)
<=> \(x\left(x^3-3x^2-6x+8\right)=0\)
<=> \(x\left[\left(x^3+x^2-2x\right)-\left(4x^2+4x-8\right)\right]=0\)
<=>\(x\left[x\left(x^2+x-2\right)-4\left(x^2+x-2\right)\right]=0\)
<=> \(x\left(x-4\right)\left(x^2+x-2\right)=0\)
<=> \(x\left(x-4\right)\left(x-1\right)\left(x+2\right)=0\)
tự làm
Tìm x, biết :
a. 3x(x-2)-x+2=0
b. 4x(x-3)-2x+6=0
c. 2x(x-4)+x-4=0
d. 2x³+4x=0
e. 3x³-6x=0
a. 3x(x-2)-x+2=0
3x(x-2)-(x-2)=0
(3x-1)(x-2)=0
=>\(\hept{\begin{cases}3x-1=0\\x-2=0\end{cases}}\)
=> \(\hept{\begin{cases}3x=1\\x=2\end{cases}}\)
=>\(\hept{\begin{cases}x=\frac{1}{3}\\x=2\end{cases}}\)
vậy x thuộc (1/3;2)
b. 4x(x-3)-2x+6=0
4x(x-3) -2(x-3)=0
(4x-2)(x-3)
=>*4x-2=0
4x=2
x=1/2
*x-3=0
x=3
vậy x thuộc (1/2;3)
a. 3x(x-2)-x+2=0
=>(x-2)(3x-1)=0
=>x-2=0 hoặc 3x-1=0
*x-2=0=>x=2
*3x-1=0=>x=\(\frac{1}{3}\)
Vậy x=2;x=\(\frac{1}{3}\)
b. 4x(x-3)-2x+6=0
=>(x-3)(4x-2)=0
=>(x-3)=0 hoặc 4x-2=0
*x-3=0=>x=3
*4x-2=0=>\(\frac{1}{2}\)
Vậy x=3; x=\(\frac{1}{2}\)
câu c, d,e thì chút nx mk gửi cho nha
Tìm x biết a) 3x^2+x)4-3x)=12 b)3x^2-2x-1=0
b: \(3x^2-2x-1=0\)
=>\(3x^2-3x+x-1=0\)
=>\(\left(x-1\right)\left(3x+1\right)=0\)
=>\(\left[{}\begin{matrix}x-1=0\\3x+1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=-\dfrac{1}{3}\end{matrix}\right.\)
a: Bạn ghi lại đề đi bạn
tìm x biết: a) (x-1)^2 - (2x)^2 = 0; b) (3x-5)^2 - x(3x-5)=0
a,\(\left(x-1\right)^2-\left(2x\right)^2=0< =>\left(x-1-2x\right)\left(x-1+2x\right)=0\)
\(< =>\left(-x-1\right)\left(3x-1\right)=0< =>\orbr{\begin{cases}x=-1\\x=\frac{1}{3}\end{cases}}\)
b,\(\left(3x-5\right)^2-x\left(3x-5\right)=0< =>\left(3x-5\right)\left(3x-5-x\right)=0\)
\(< =>\orbr{\begin{cases}x=\frac{5}{3}\\x=\frac{5}{2}\end{cases}}\)
a, \(\left(x-1\right)^2-\left(2x\right)^2=0\Leftrightarrow\left(x-1-2x\right)\left(x-1+2x\right)=0\)
\(\Leftrightarrow\left(x+1\right)\left(3x-1\right)=0\Leftrightarrow x=-1;x=\frac{1}{3}\)
b, \(\left(3x-5\right)^2-x\left(3x-5\right)=0\)
\(\Leftrightarrow\left(3x-5\right)\left(3x-5-x\right)=0\Leftrightarrow\left(3x-5\right)\left(2x-5\right)=0\Leftrightarrow x=\frac{5}{3};x=\frac{5}{2}\)
Tìm x biết: 1) (x+1)(3-x) / (4-2x) lớn hơn hoặc =0
2) (x+3)(3x-2) / (2x+1)(4-3x) >0
1,X=-1 hoặc 3
2,Tìm x sao cho (x+3) và (3x-2) ko bằng 0
tìm x biết :
a) 2x . ( x-3 ) + 6 . (3x -3 )=0
b) 3x . (2x - 5) - 15 . ( 5 - 2x )
a) \(2x\left(x-3\right)+6\left(3x-3\right)=0\)
\(\Leftrightarrow2x^2-6x+18x-18=0\)
\(\Leftrightarrow2x^2+12x-18=0\)
Mà \(2x^2\ge0\)
\(\Rightarrow x\in\varnothing\)
a)=>2x^2-6x+18x-18=0 b)=>6x^2-15x-75-30x =????
=>2x^2+12x=0+18
=>2x^2+12x=18
=>x.(2x+12)=18 (tự làm phần còn lai)
a, \(2x\left(x-3\right)+6\left(3x-3\right)=0\)
\(\Leftrightarrow2x^2-6x+18x-18=0\)
\(\Leftrightarrow2x^2+12x-18=0\)
=> Phương trình vô nghiệm
b,Sử đề : \(3x\left(2x-5\right)-15\left(5-2x\right)=0\)
\(\Leftrightarrow6x^2-15x-75+30x=0\)
\(\Leftrightarrow6x^2+15x-75=0\)
\(\Leftrightarrow3\left(x+5\right)\left(2x-5\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x=-5\\x=\frac{5}{2}\end{cases}}\)
Bài 2: Tìm x, biết: a) (x + 2)^2 – 2(x + 2)(x – 5) = 0. b) 2x^2 + 3x – 5 = 0. c) x + 2 ^2 x 2 + 2x^3 = 0. d) (3x-1)^2-4(x+5)^2=0
a: \(\Leftrightarrow\left(x+2\right)\left(x+2-2x+10\right)=0\)
\(\Leftrightarrow x\in\left\{-2;12\right\}\)
Tìm x biết 2x^3-3x^2+3x-1=0
\(2x^3-3x^2+3x-1=0\)
\(\Leftrightarrow2x^3-2x^2-x^2+2x+x-1=0\)
\(\Leftrightarrow\left(2x^3-2x^2+2x\right)-\left(x^2-x+1\right)=0\)
\(\Leftrightarrow2x\left(x^2-x+1\right)-\left(x^2-x+1\right)=0\)
\(\Leftrightarrow\left(2x-1\right)\left(x^2-x+1\right)=0\)
\(TH1:2x-1=0\Leftrightarrow x=\frac{1}{2}\)
\(TH2:x^2-x+1=0\)
\(\Leftrightarrow\left(x-\frac{1}{2}\right)^2+\frac{3}{4}=0\)
Mà \(\left(x-\frac{1}{2}\right)^2+\frac{3}{4}>0\)nên loại TH2
Vậy \(x=\frac{1}{2}\)
2x3 - 3x2 + 3x - 1 = 0
(2x - 1)(x2 - x + 1) = 0
Vì: x2 - x + 1 > 0 nên:
2x - 1 = 0
2x = 0 + 1
2x = 1
x = 1/2
\(2x^3-3x^2+3x-1=0\)
\(\Rightarrow\left(x-1\right)^3+x^3=0\)
\(\Rightarrow\left(2x-1\right)\left(x^2-2x+1-x^2+x+x^2\right)=0\)
\(\Rightarrow\left(2x-1\right)\left(x^2-x+1\right)=0\)
Vì \(x^2-x+1=\left(x-\frac{1}{2}\right)^2+\frac{5}{4}\ge\frac{5}{4}\forall x\)
\(\Rightarrow2x-1=0\)
\(\Rightarrow x=\frac{1}{2}\)