tìm x biết :
a) x . (x + 2 ) = 0
b) (1/2 + 1/3 - 1/4 ) . ( x - 3 ) = 0
Tìm x biết :
a)(x-1)^2+(3-x)(3+x)=0
b)(x-2)^2-(2x+1)^2=0
a) \(\left(x-1\right)^2+\left(3-x\right)\left(3+x\right)=0\)
\(\Rightarrow x^2-2x+1+9-x^2=0\)
\(\Rightarrow2x=10\Rightarrow x=5\)
b) \(\left(x-2\right)^2-\left(2x+1\right)^2=0\)
\(\Rightarrow\left(x-2-2x-1\right)\left(x-2+2x+1\right)=0\)
\(\Rightarrow-\left(x+3\right)\left(3x-1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=-3\\x=\dfrac{1}{3}\end{matrix}\right.\)
a) \(\left(x-1\right)^2+\left(3-x\right)\left(3+x\right)=0\\ \Leftrightarrow x^2-2x+1+9-x^2=0\\ \Leftrightarrow-2x=-10\\ \Leftrightarrow x=5\)
b) \(\left(x-2\right)^2-\left(2x+1\right)^2=0\\ \Leftrightarrow x^2-4x+4-4x^2-4x-1=0\\ \Leftrightarrow-3x^2-8x+3=0\\ \Leftrightarrow3x^2+8x-3=0\\ \Leftrightarrow\left(3x^2+9x\right)-\left(x+3\right)=0\\ \Leftrightarrow\left(x+3\right)\left(3x-1\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=-3\\x=\dfrac{1}{3}\end{matrix}\right.\)
Tìm x biết: (x + 2)^2 - (x + 2)(x - 3) = 0
Tìm x biết :
a,(x+2)^2-(x+2)(x-3)=0
b,2x^3-4x^2+2x=0
c,(x-1)^2-(2x+1)^2=0
\(a,\Leftrightarrow\left(x+2\right)\left(x+2-x+3\right)=0\\ \Leftrightarrow5\left(x+2\right)=0\Leftrightarrow x=-2\\ b,\Leftrightarrow2x\left(x-1\right)^2=0\Leftrightarrow\left[{}\begin{matrix}x=0\\x=1\end{matrix}\right.\\ c,\Leftrightarrow\left(x-1-2x-1\right)\left(x-1+2x+1\right)=0\\ \Leftrightarrow3x\left(-x-2\right)=0\Leftrightarrow-3x\left(x+2\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x=-2\end{matrix}\right.\)
Tìm các số hữu tỉ x, biết :
a)\(\dfrac{-5}{x-3}\)<0
b)\(\dfrac{3-x}{x^2+1}\)≥0
c)\(\dfrac{\left(x-1\right)^2}{x-2}\)<0
\(a,\dfrac{-5}{x-3}< 0\Leftrightarrow x-3>0\left(-5< 0\right)\Leftrightarrow x>3\\ b,\dfrac{3-x}{x^2+1}\ge0\Leftrightarrow3-x\ge0\left(x^2+1>0\right)\Leftrightarrow x\le3\\ c,\dfrac{\left(x-1\right)^2}{x-2}< 0\Leftrightarrow x-2< 0\left[\left(x-1\right)^2\ge0\right]\Leftrightarrow x< 2\)
1.rút gọn bt A= (x+2)3-2x(x+3)+(x3-8):(x-2)
2. tìm x biết:
a. 3x2-12x=0
b.4x2-1-4(1-2x)=0
Tìm x biết :
a/ ( x +1 )^2 - 3 ( x + 1 ) = 0
b/ 2 ( 3x - 2 )^2 = 9x^2 - 4
a: Ta có: \(\left(x+1\right)^2-3\left(x+1\right)=0\)
\(\Leftrightarrow\left(x+1\right)\left(x-2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-1\\x=2\end{matrix}\right.\)
b: Ta có: \(2\left(3x-2\right)^2=9x^2-4\)
\(\Leftrightarrow2\left(3x-2\right)^2-\left(3x-2\right)\left(3x+2\right)=0\)
\(\Leftrightarrow\left(3x-2\right)\left(6x-4-3x-2\right)=0\)
\(\Leftrightarrow\left(3x-2\right)\left(3x-6\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{2}{3}\\x=2\end{matrix}\right.\)
Bài 7. Tìm x,biết:
a) x-3x2=0 e) 5x(3x-1)+x(3x-1)-2(3x-1)=0
b) (x+3)2-x(x-2)=13 c) (x-4)2-36=0
d) x2-7x+12=0 g) x2-2018x-2019=0
Bài 8. Tìm x, biết
a) (2x-1)2=(x+5)2 b) x2-x+1/4
c) 4x4-101x2+25=0 d) x3-3x2+9x-91=0
Tìm x
a) 4(x + 1)2 + (2x + 1)2 - 8(x – 1)(x + 1) - 11=0
b)(x + 3)2 – (x – 4)(x + 8) – 1 = 0
a: Ta có: \(4\left(x+1\right)^2+\left(2x+1\right)^2-8\left(x-1\right)\left(x+1\right)-11=0\)
\(\Leftrightarrow4x^2+8x+4+4x^2+4x+1-8x^2+8-11=0\)
\(\Leftrightarrow12x=-2\)
hay \(x=-\dfrac{1}{6}\)
b: Ta có: \(\left(x+3\right)^2-\left(x-4\right)\left(x+8\right)-1=0\)
\(\Leftrightarrow x^2+6x+9-x^2-4x+32-1=0\)
\(\Leftrightarrow2x=-40\)
hay x=-20
Tìm x :
a , ( x-1 )( x-4 ) > 0
b , ( x-6 )( x-7 ) < 0
c , ( x-1 )( x-2 ) bé hơn bằng 0
d , ( x-2 )( x- 2/3 ) lớn hơn bằng 0 .
a) Ta có: (x-1)(x-4)>0
\(\Leftrightarrow\left[{}\begin{matrix}x-4>0\\x-1< 0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x>4\\x< 1\end{matrix}\right.\)
b) Ta có: (x-6)(x-7)<0
\(\Leftrightarrow\left\{{}\begin{matrix}x-6>0\\x-7< 0\end{matrix}\right.\Leftrightarrow6< x< 7\)
c) Ta có: \(\left(x-1\right)\left(x-2\right)\le0\)
\(\Leftrightarrow\left\{{}\begin{matrix}x-1\ge0\\x-2\le0\end{matrix}\right.\Leftrightarrow1\le x\le2\)
d) Ta có: \(\left(x-2\right)\left(x-\dfrac{2}{3}\right)\ge0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-2\ge0\\x-\dfrac{2}{3}\le0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x\ge2\\x\le\dfrac{2}{3}\end{matrix}\right.\)
a) Ta có: (x-1)(x-4)>0
⇔[x−4>0x−1<0⇔[x>4x<1⇔[x−4>0x−1<0⇔[x>4x<1
b) Ta có: (x-6)(x-7)<0
⇔{x−6>0x−7<0⇔6<x<7⇔{x−6>0x−7<0⇔6<x<7
c) Ta có: (x−1)(x−2)≤0(x−1)(x−2)≤0
⇔{x−1≥0x−2≤0⇔1≤x≤2⇔{x−1≥0x−2≤0⇔1≤x≤2
d) Ta có: (x−2)(x−23)≥0(x−2)(x−23)≥0
⇔⎡⎣x−2≥0x−23≤0⇔⎡⎣x≥2x≤23
1.tìm x,y biết
a, x.(y-3)≥0
b, (2.x-1).(y-1)≤0
c,(x-1).(2.k+1)≥0
2. tìm x,y ϵ Z biết
a, x(x+3)=0
b,(x-2).(5-x)=0
c,(x-1).(x^2+1)=0
d, x.y+3.x-7.y=21
e,x.y+3.x-2y=11
Bài 2:
a: =>x=0 hoặc x+3=0
=>x=0 hoặc x=-3
b: =>x-2=0 hoặc 5-x=0
=>x=2 hoặc x=5
c: =>x-1=0
hay x=1
1) Phân tích đa thức thành nhân tử
a) 2x4-4x3+2x2
b) 2x2-2xy+5x-5y
2) Tìm x, biết:
a) 4x(x-3)-x+3=0
b)(2x-3)2-(x+1)2=0
1.
a) \(2x^4-4x^3+2x^2\)
\(=2x^2\left(x^2-2x+1\right)\)
\(=2x^2\left(x-1\right)^2\)
b) \(2x^2-2xy+5x-5y\)
\(=\left(2x^2-2xy\right)+\left(5x-5y\right)\)
\(=2x\left(x-y\right)+5\left(x-y\right)\)
\(=\left(x-y\right)\cdot\left(2x+5\right)\)
2 .
a,
\(4x\left(x-3\right)-x+3=0\)
⇒\(4x\left(x-3\right)-\left(x-3\right)=0\)
⇒\(\left(x-3\right)\left(4x-1\right)=0\)
⇒\(\left[{}\begin{matrix}x-3=0\\4x-1=0\end{matrix}\right.\)
⇔\(\left[{}\begin{matrix}x=3\\4x=1\end{matrix}\right.\)
⇔\(\left[{}\begin{matrix}x=3\\x=\dfrac{1}{4}\end{matrix}\right.\)
vậy \(x\in\left\{3;\dfrac{1}{4}\right\}\)
b,
\(\)\(\left(2x-3\right)^2-\left(x+1\right)^2=0\)
⇒\(\left(2x-3-x-1\right)\left(2x-3+x+1\right)\) = 0
⇒\(\left(x-4\right)\left(3x-2\right)=0\)
⇔\(\left[{}\begin{matrix}x-4=0\\3x-2=0\end{matrix}\right.\)
⇔\(\left[{}\begin{matrix}x=4\\3x=2\end{matrix}\right.\)
⇔\(\left[{}\begin{matrix}x=4\\x=\dfrac{2}{3}\end{matrix}\right.\)
vậy \(x\in\left\{4;\dfrac{2}{3}\right\}\)