Tìm x biết: (2x-1)(4x-16)>0
Tìm x biết :
a) (3x³ + x² – 13x + 5) : (x² + 2x – 1) = 10
b) (x⁴ – 2x² – 8) : (x – 2) = 0
c) (x²-4x) : (x²-8x+16) = 0
\(a,\Leftrightarrow\dfrac{3x^3+6x^2-3x-5x^2-10x+5}{x^2+2x-1}=10\\ \Leftrightarrow\dfrac{3x\left(x^2+2x-1\right)-5\left(x^2+2x-1\right)}{x^2+2x-1}=10\\ \Leftrightarrow3x-5=10\Leftrightarrow3x=15\Leftrightarrow x=5\\ b,\Leftrightarrow\left(x^4+2x^2-4x^2-8\right):\left(x-2\right)=0\\ \Leftrightarrow\left[\left(x^2-4\right)\left(x^2+2\right)\right]:\left(x-2\right)=0\\ \Leftrightarrow\left[\left(x-2\right)\left(x+2\right)\left(x^2+2\right)\right]:\left(x-2\right)=0\\ \Leftrightarrow\left(x+2\right)\left(x^2+2\right)=0\Leftrightarrow x=-2\left(x^2+2>0\right)\\ c,\Leftrightarrow\dfrac{x\left(x-4\right)}{\left(x-4\right)^2}=0\Leftrightarrow\dfrac{x}{x-4}=0\Leftrightarrow x=0\)
b: \(\Leftrightarrow x^4-4x^2+2x^2-8=0\)
hay x=-2
Tìm x biết:
a:(x-1)^3-x(x-2)^2-(x-2)=0
b:(2x+5)(2x-7)-(4x+3)^2=16
a) (x - 1)3 - x(x - 2)2 - (x - 2) = 0
<=> x3 - 2x2 + x - x2 + 2x - 1 - x3 + 4x2 - 4x - x + 2 = 0
<=> x2 - 2x + 1 = 0
<=> x2 - 2.x.1 + 12 = 0
<=> (x - 1)2 = 0
x - 1 = 0
x = 0 + 1
x = 1
=> x = 1
a)Ta có : \(\left(x-1\right)^3-x\left(x-2\right)^2-\left(x-2\right)=0\)
\(=>\left(x-1\right)^3-\left(x^2-2x\right)\left(x-2\right)-\left(x-2\right)=0\)
\(=>\left(x-1\right)^3-\left(x-2\right)\left(x^2-2x+1\right)=0\)
\(=>\left(x-1\right)^3-\left(x-2\right)\left(x-1\right)^2=0\)
\(=>\left(x-1\right)^2\left(x-1-x+2\right)=0\)
\(=>\left(x-1\right)^2=0=>x-1=0=>x=1\)
Vậy x=1
b)(2x+5)(2x-7)-(4x+3)2=16
\(=>4x^2-4x-35-16x^2-24x-9-16=0\)
\(=>-\left(12x^2+28x+60\right)=0\)
\(=>12\left(x^2+\frac{7}{3}x+\frac{5}{3}\right)=0\)
\(=>x^2+\frac{7}{3}x+\frac{49}{36}+\frac{11}{36}=0=>\left(x+\frac{7}{6}\right)^2+\frac{11}{36}=0\)
Lại có \(\left(x+\frac{7}{6}\right)^2\ge0=>\left(x+\frac{7}{6}\right)^2+\frac{11}{36}\ge\frac{11}{36}>0\)
Vậy ko có giá trị nào của x thỏa mãn đề bài
\(=>x^2+\frac{7}{3}x+\frac{49}{36}+\frac{11}{36}=0=>\left(x+\frac{7}{6}\right)^2+\frac{11}{36}=0\)
Tìm x, biết:
a) (2x+2)(x-1)-(x+2)(2x+1)=0;
b)(3x+1)(2x-3)-6x(x+2)=16;
c)(12x-5)(4x-1)+(3x-7)(1-16x)=81
mn ơi giúp mik vs ạ :<
a: =>2x^2-2x+2x-2-2x^2-x-4x-2=0
=>-5x-4=0
=>x=-4/5
b: =>6x^2-9x+2x-3-6x^2-12x=16
=>-19x=19
=>x=-1
c: =>48x^2-12x-20x+5+3x-48x^2-7+112x=81
=>83x=83
=>x=1
Tìm x biết
a) (x-3)^2 -4=0
b) ( 2x+3)^2 - (2x+1)(2x-1) =22
c) (4x+3)(4x-3) -(4x-5)^2 =16
d) x^3 -9x^2 +27x-27 =-8
e) (x+1)^3 - x^2(x+3) =2
a) \(\left(x-3\right)^2-4=0\)
\(\left(x-3\right)^2=0+4\)
\(\left(x-3\right)^2=4\)
\(\left(x-3\right)^2=\pm4\)
\(\left(x-3\right)^2=\pm2^2\)
\(\orbr{\begin{cases}x-3=2\\x-3=-2\end{cases}}\)
\(\orbr{\begin{cases}x=5\\x=1\end{cases}}\)
b) \(\left(2x+3\right)^2-\left(2x+1\right)\left(2x-1\right)=22\)
\(4x^2+12x+9-4x^2+1=22\)
\(12x+10=22\)
\(12x=22-10\)
\(12x=12\)
\(x=1\)
c) \(\left(4x+3\right)\left(4x-3\right)-\left(4x-5\right)^2=16\)
\(16x^2-9-16x^2+40x-25=16\)
\(-34+40x=16\)
\(40x=16+34\)
\(40x=50\)
\(x=\frac{50}{40}=\frac{5}{4}\)
d) \(x^3-9x^2+27x-27=-8\)
\(x^3-9x^2+27x-27+8=0\)
\(x^3-9x^2+27x-19=0\)
\(\left(x^2-8x+19\right)\left(x-1\right)=0\)
Vì \(\left(x^2-8x+19\right)>0\) nên:
\(x-1=0\)
\(x=1\)
e) \(\left(x+1\right)^3-x^2\left(x+3\right)=2\)
\(x^3+2x^2+x+x^2+2x+1-x^2-3x^2=2\)
\(3x+1=2\)
\(3x=2-1\)
\(3x=1\)
\(x=\frac{1}{3}\)
tìm x, biết
x^2 -2x=0
(3x-1)^2-16=0
x^2-25x=0
(4x-1)^2-9=0
a) \(x^2-2x=0\)
\(x\left(x-2\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x=0\\x-2=0\end{cases}\Rightarrow\orbr{\begin{cases}x=0\\x=2\end{cases}}}\)
b) \(\left(3x-1\right)^2-16=0\)
\(\left(3x-1\right)^2-4^2=0\)
\(\left(3x-1-4\right)\left(3x-1+4\right)=0\)
\(\left(3x-5\right)\left(3x+3\right)=0\)
\(\Rightarrow\orbr{\begin{cases}3x-5=0\\3x+3=0\end{cases}\Rightarrow\orbr{\begin{cases}x=\frac{5}{3}\\x=-1\end{cases}}}\)
c) \(x^2-25x=0\)
\(x\left(x-25\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x=0\\x-25=0\end{cases}\Rightarrow\orbr{\begin{cases}x=0\\x=25\end{cases}}}\)
d) \(\left(4x-1\right)^2-9=0\)
\(\left(4x-1\right)^2-3^2=0\)
\(\left(4x-1-3\right)\left(4x-1+3\right)=0\)
\(\left(4x-4\right)\left(4x+2\right)=0\)
\(\Rightarrow\orbr{\begin{cases}4x-4=0\\4x+2=0\end{cases}\Rightarrow\orbr{\begin{cases}x=1\\x=\frac{-1}{2}\end{cases}}}\)
a) \(x^2-2x=0\)
\(x.\left(x-2\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x=0\\x-2=0\end{cases}\Rightarrow\orbr{\begin{cases}x=0\\x=2\end{cases}}}\)
vậy..
b) \(\left(3x-1\right)^2-16=0\)
\(\left(3x-1\right)^2=16\)
\(\left(3x-1\right)^2=4^2=\left(-4\right)^2\)
\(\Rightarrow\orbr{\begin{cases}3x-1=4\\3x-1=-4\end{cases}\Rightarrow\orbr{\begin{cases}x=\frac{5}{3}\\x=-1\end{cases}}}\)
vậy ...
c) \(x^2-25x=0\)
\(x.\left(x-25\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x=0\\x-25=0\end{cases}\Rightarrow\orbr{\begin{cases}x=0\\x=25\end{cases}}}\)
vậy ....
d) \(\left(4x-1\right)^2-9=0\)
\(\left(4x-1\right)^2=3^2=\left(-3\right)^2\)
\(\Rightarrow\orbr{\begin{cases}4x-1=3\\4x-1=-3\end{cases}\Rightarrow\orbr{\begin{cases}x=1\\x=\frac{1}{2}\end{cases}}}\)
vậy ...
a)\(x^2-2x=0\)
\(\Rightarrow x\left(x-2\right)=0\)
\(\Rightarrow\hept{\begin{cases}x=0\\x-2=0\end{cases}}\Rightarrow\hept{\begin{cases}x=0\\x=2\end{cases}}\)
b)\(\left(3x-1\right)^2-16=0\)
\(\left(3x-1-4\right)\left(3x-1+4\right)=0\)
\(\Rightarrow\hept{\begin{cases}3x-1-4=0\\3x-1+4=0\end{cases}}\Rightarrow\hept{\begin{cases}x=\frac{5}{3}\\x=-1\end{cases}}\)
c)\(x^2-25x=0\)
\(x\left(x-25\right)=0\)
\(\Rightarrow\hept{\begin{cases}x=0\\x-25=0\end{cases}\Rightarrow}\hept{\begin{cases}x=0\\x=25\end{cases}}\)
d)\(\left(4x-1\right)^2-9=0\)
\(\left(4x-1-3\right)\left(4x-1+3\right)=0\)
\(\Rightarrow\hept{\begin{cases}4x-1-3=0\\4x-1+3=0\end{cases}\Rightarrow\hept{\begin{cases}x=1\\x=-\frac{1}{2}\end{cases}}}\)
Tìm x, biết :
a) ( x - 4 )( x^2 + 4x + 16 ) - x( x^2 - 6 ) = 2
b) ( 2x - 1 )^2 - ( 3x + 4 )^2 = 0
a) x^3 - 64 - x^3 +6x = 2
(x^3 - x^3) + 6x = 2+64 quy tắc chuyển vế nhé bạn
6x = 66
x = 66:11
x = 6
Tìm x
2x-7+(x-14)=0
x^2-6x=0
(x-3)(16-4x)=0
(x-3)-(16-4x)=0
(x-3)+(16-4x)=0
Mấy câu này khá giống nhau nhé anh (câu 1 giống câu 4 và 5, cấu 2 giống câu 3) =)))
Câu 1: 2x - 7 + (x - 14) = 0
<=> 3x -21 = 0
<=> 3x = 21 => x = 7
Câu 2:
x2 - 6x = 0 <=> x.(x - 6) = 0 => \(\orbr{\begin{cases}x=0\\x-6=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=0\\x=6\end{cases}}\)
Chúc anh học tốt !!!
Câu 1, 2 có người làm rồi nên mik làm tiếp cho mấy câu tiếp. Cứ áp dụng A.B = 0 => A = 0 hoặc B = 0
3; ( x - 3 )( 16 - 4x ) = 0
=> x - 3 = 0 hoặc 16 - 4x = 0
=> x = 3 hoặc x = 4
Vậy x = 3 hoặc x = 4.
4; ( x - 3 ) - ( 16 - 4x ) = 0
=> x - 3 - 16 + 4x = 0
=> ( x + 4x ) - ( 3 + 16 ) = 0
=> 5x - 19 = 0
=> x = 19/5
Vậy x = 19/5
5; ( x + 3 ) + ( 16 - 4x ) = 0
=> x + 3 + 16 - 4x = 0
=> ( x - 4x ) + ( 16 + 3 ) = 0
=> 3x + 19 = 0
=> x = 19/3
Vậy x = 19/3
Tìm x biết
a, ( 3x - 1 )^2 - 3x( 3x + 2 ) = 0
b, ( 2x + 3)^2 = 4x(x + 1 )
c, ( 1 / 2 - 4)^2 + 3 / 2x ( x - 1 ) = ( x + 1 / 2)^2
d, x^2 - 4x + 4 = 16
a, ( 3x - 1 )^2 - 3x( 3x + 2 ) = 0
<=>9x2-6x+1-9x2-6x=0
<=>-12x+1=0
<=>-12x=-1
<=>x=1/12
b, ( 2x + 3)^2 = 4x(x + 1 )
<=>(2x+3)2-4x(x+1)=0
<=>4x2+12x+9-4x2-4x=0
<=>8x+9=0
<=>8x=-9
<=>x=-9/8
c) vô fx gõ lại
d)x2-4x+4=16
<=>(x-2)2-16=0
<=>(x-2)2-42=0
<=>(x-2+4)(x-2-4)=0
<=>(x+2)(x-6)=0
<=>x+2=0 hoặc x-6=0
<=>x=-2 hoặc x=6
BT2: Tìm x 2, 3x(x-4)+2x-8=0 3, 4x(x-3)+x^2-9=0 4, x(x-1)-x^2+3x=0 5, x(2x-1)-2x^2+5x=16
2: \(3x\left(x-4\right)+2x-8=0\)
=>\(3x\left(x-4\right)+2\left(x-4\right)=0\)
=>\(\left(x-4\right)\left(3x+2\right)=0\)
=>\(\left[{}\begin{matrix}x-4=0\\3x+2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=4\\x=-\dfrac{2}{3}\end{matrix}\right.\)
3: 4x(x-3)+x2-9=0
=>\(4x\left(x-3\right)+\left(x+3\right)\left(x-3\right)=0\)
=>\(\left(x-3\right)\left(4x+x+3\right)=0\)
=>\(\left(x-3\right)\left(5x+3\right)=0\)
=>\(\left[{}\begin{matrix}x-3=0\\5x+3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-\dfrac{3}{5}\end{matrix}\right.\)
4: \(x\left(x-1\right)-x^2+3x=0\)
=>\(x^2-x-x^2+3x=0\)
=>2x=0
=>x=0
5: \(x\left(2x-1\right)-2x^2+5x=16\)
=>\(2x^2-x-2x^2+5x=16\)
=>4x=16
=>x=4