Tìm x biết
( x - 3 ) ( x - 4 ) > 0
Bài 13: Tìm x biết: a) (x-2)(x-3)-D0. b) (x-3)(x-4)-0. c) (x-7)(6-x)=0. d) (x-3)(x-13)=0. The Bài 14: Tìm x biết: a) (12-x)(2-x)=0. b) (x-33)(11-x)=0. c) (21-x)(12-x)=0. d) (50-x)(x-150) =0. Bài 15: Tìm x biết: a) 2x +x = 45. b) 2x +7x = 918. c) 2x+3x 60+5. d) 11x+22x 33.2.
tìm x , biết :
a, ( x mũ 3 - 4 x mũ 2 ) - ( x -4 ) = 0
b, x mũ 5 - 9x = 0
c, ( x mxu 3 - x mũ 2 ) mũ 2 - 4 x mũ 2 + 8x - 4 = 0
a/
\(x^3-4x^2-\left(x-4\right)=0\)
\(\Leftrightarrow x^2\left(x-4\right)-\left(x-4\right)=0\)
\(\Leftrightarrow\left(x-4\right)\left(x^2-1\right)=0\)
\(\Leftrightarrow\left(x-4\right)\left(x-1\right)\left(x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-4=0\\x-1=0\\x+1=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=4\\x=1\\x=-1\end{matrix}\right.\)
b/
\(x^5-9x=0\)
\(\Leftrightarrow x\left(x^4-9\right)=x\left(x^2-3\right)\left(x^2+3\right)=0\)
\(\Leftrightarrow x\left(x-\sqrt{3}\right)\left(x+\sqrt{3}\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\sqrt{3}\\x=-\sqrt{3}\end{matrix}\right.\)
c/
\(\left(x^3-x^2\right)^2-4x^2+8x-4=0\)
\(\Leftrightarrow x^4\left(x-1\right)^2-4\left(x-1\right)^2=0\)
\(\Leftrightarrow\left(x-1\right)^2\left(x^4-4\right)=0\)
\(\Leftrightarrow\left(x-1\right)^2\left(x^2-2\right)\left(x^2+2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-1=0\\x^2-2=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=\pm\sqrt{2}\end{matrix}\right.\)
Tìm x thuộc Z biết: a) x ( x - 2) = 0 b) x ( x + 7 ) = 0 c) ( x + 6) ( x - 4) = 0; d) ( x - 3) ( 2 x 2 + 3) = 0
tìm x biết :
4x(x+1) = 8(x+1)
x(2x+1) +\(\dfrac{1}{3}-\dfrac{2}{3}x=0\)
x(x-4) +(x-4)2 =0
3) \(x\left(x-4\right)+\left(x-4\right)^2=0\Leftrightarrow\left(x-4\right)\left(x+x-4\right)=0\Leftrightarrow2\left(x-4\right)\left(x-2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-4=0\\x-2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=4\\x=2\end{matrix}\right.\)
4x.(x+1)-8(x+1)=0
(4x-8)(x+1)=0
suy ra x=2 hoặc x=-1
1) \(4x\left(x+1\right)=8\left(x+1\right)\Leftrightarrow4x^2+4x=8x+8\Leftrightarrow4x^2-4x-8=0\Leftrightarrow x^2-x-2=0\Leftrightarrow\left(x-2\right)\left(x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-1\end{matrix}\right.\)
Tìm x, biết:
a) (x - 8.25).4 = 0;
b) (x - 50): 4 - 3 = 97;
c) 8.(22 -x) = 8;
d) (x : 3-3)(x: 6-6) = 0.
a) x = 200
b) x = 450
c) x = 21
d) x = 9 hoặc x = 36
Tìm x, biết.
a) x+ 5x2 = 0 b)(x+3)2+(4+x)(4-x)=10
c) 5x( x – 1) = x - 1 d) x2 -2x -3 = 0
\(a,x+5x^2=0\\ \Rightarrow a,x\left(1+5x\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=0\\x=-\dfrac{1}{5}\end{matrix}\right.\\ b,\left(x+3\right)^2+\left(4+x\right)\left(4-x\right)=0\\ \Rightarrow x^2+6x+9+16-x^2=0\\ \Rightarrow6x+25=0\\ \Rightarrow6x=-25\\ \Rightarrow x=-\dfrac{25}{6}\)
\(c,5x\left(x-1\right)=x-1\\ \Rightarrow c,5x\left(x-1\right)-\left(x-1\right)\\ \Rightarrow\left(x-1\right)\left(5x-1\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=1\\x=\dfrac{1}{5}\end{matrix}\right.\\ d,x^2-2x-3=0\\ \Rightarrow\left(x^2-3x\right)+\left(x-3\right)=0\\ \Rightarrow x\left(x-3\right)+\left(x-3\right)=0\\ \Rightarrow\left(x+1\right)\left(x-3\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=-1\\x=3\end{matrix}\right.\)
Tìm x biết: a)x(x-3)+x-3=0 b)(5x-4)^2-16^2=0
Tìm x biết : |3 - |x-1| | = 2
Tìm x, y biết 4 |x+3| + |2y - 1| = 0
Bài 5. Tìm x ∈ Z biết:
a) (x – 2)(– 4 – x2) > 0
b) (x2 + 2)(x + 3) > 0
c) (x + 3)(x – 4) > 0. Mik sẽ tick nha
\(a,\Leftrightarrow\left(2-x\right)\left(x^2+4\right)>0\Leftrightarrow2-x>0\Leftrightarrow x< 2\\ b,\Leftrightarrow x+3>0\Leftrightarrow x>-3\\ c,\Leftrightarrow\left[{}\begin{matrix}x< -3\\x>4\end{matrix}\right.\)
b: \(\Leftrightarrow x+3>0\)
hay x>-3
Tìm x biết
a,x^5+x^4+x+1=0
b,x^4+3x^3-x-3=0
Ta có : x5 + x4 + x + 1 = 0
<=> x4(x + 1) + (x + 1) = 0
<=> (x + 1)(x4 + 1) = 0
\(\Leftrightarrow\orbr{\begin{cases}x+1=0\\x^4+1=0\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=-1\\x^4=-1\end{cases}}\)
Vậy x = -1
Ta có : x4 + 3x3 - x - 3 = 0
<=> x3(x + 3) - (x + 3) = 0
<=> (x + 3) (x3 - 1) = 0
\(\Leftrightarrow\orbr{\begin{cases}x+3=0\\x^3-1=0\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=-3\\x^3=1\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=-3\\x=1\end{cases}}\)
Vậy x thuộc {-3;1}