Tim x, biet:
(2x-1)2-(2x+3).(2x-3)=0
Tim xthuoc Z biet:
1,|2x-5|-|2x+9|=0
2,|x+1|-|x+2|-|3-x|=7
3,|2x+3|+|3x+2|-|4-x|=10
tim x biet (2x+1)+(2x+2)+...+(2x+2015)=0
Có 2015 số hạng
Tổng là (2x+1+2x+2015).2015:2=0
4x+2016=0
4x=-2016
x=-504
Ủng hộ mk nha
( 2x + 1 ) + ( 2x + 2 ) + ... + ( 2x + 2015 ) = 0
=> ( 2x + 2x + .. + 2x ) + ( 1 + 2 + ... + 2015 ) = 0
2015 số 2x
=> 2x . 2015 + 2031120 = 0
=> 2x . 2015 = 0 - 2031120
=> 2x . 2015 = - 2031120
=> 2x = ( - 2031120 ) : 2015
=> 2x = - 1008
=> x = ( - 1008 ) : 2
=> x = - 504
=> ( 2x + 2x + .... + 2x + 2x ) + ( 1 + 2 + 3 + .... + 2015 ) = 0
=> ( 2x.2015 ) + { [ 2015.( 2015 + 1 ] : 2 } = 0
=> 4030x + [ ( 2015 . 2016 ) : 2 ] = 0
=> 4030x + ( 4062240 : 2 ) = 0
=> 4030x + 2031120 = 0
=> 4030x = - 2031120
=> x = - 2031120 : 4030 = - 504
Vậy x = - 504
tim x biet (2x+1)+(2x+2)+...+(2x+2015)=0
Có tất cả số 2x là:
(2015-1):1+1=2015(số)
Ta có:(2x+1)+(2x+2)+............+(2x+2015)=0
=>2015*2x+(1+2+3+............+2015)=0
=>4030x+2031120=0
=>4030x=-2031120
=>x=-504
tim x biet
|2x+1|+|2x+2|+|2x+3|+...+|2x+1007|=2015x
Lời giải:
Ta thấy:
$2015x=|2x+1|+|2x+2|+...+|2x+1007|\geq 0$
$\Rightarrow x\geq 0$.
Khi đó:
$|2x+1|=2x+1, |2x+2|=2x+2, |2x+3|=2x+3,...., |2x+1007|=2x+1007$.
Phương trình trở thành:
$(2x+1)+(2x+2)+....+(2x+1007)=2015x$
$\Rightarrow \underbrace{(2x+2x+...+2x)}_{1007}+(1+2+3+...+1007)=2015x$
$\Rightarrow 2x.1007+1007.1008:2=2015x$
$\Rightarrow 2014x+507528=2015x$
$\Rightarrow x=507528$
|(x+1/2).|2x-3/4||=2x-3/4 tim x biet
tim x biet: ||x-1/2|.|2x-3/4||=2x-3/4
tim x biet: ||x-1/2|.|2x-3/4||=2x-3/4
\(\left|x-\dfrac{1}{2}\right|\left|2x-\dfrac{3}{4}\right|=2x-\dfrac{3}{4}\)
\(\left\{{}\begin{matrix}\left|x-\dfrac{1}{2}\right|\ge0\\\left|2x-\dfrac{3}{4}\right|\ge0\end{matrix}\right.\)
\(\Rightarrow2x-\dfrac{3}{4}\ge0\)
\(\Rightarrow\left|2x-\dfrac{3}{4}\right|=2x-\dfrac{3}{4}\)
\(\Rightarrow\left|x-\dfrac{1}{2}\right|=1\)
\(\Rightarrow\left[{}\begin{matrix}x-\dfrac{1}{2}=1\Rightarrow x=\dfrac{3}{2}\\x-\dfrac{1}{2}=-1\Rightarrow x=-\dfrac{1}{2}\end{matrix}\right.\)
\(2x-\dfrac{3}{4}\ge0\Rightarrow2x\ge\dfrac{3}{4}\Rightarrow x\ge\dfrac{3}{2}\)
Vậy xảy ra khi:
\(x=\dfrac{3}{2}\)
|(x+1/2).|2x-3/4||=2x-3/4 tim x biet
Tim x biet:|x-2|+|3-2x|=2x+1
\(\Leftrightarrow\left|x-2\right|+\left|2x-3\right|=2x+1\)
Trường hợp 1: x<3/2
Pt sẽ là 3-2x+2-x=2x+1
=>-3x+5=2x+1
=>-5x=-4
hay x=4/5(nhận)
Trường hợp 2: 3/2<=x<2
Pt sẽ là 2x-3+2-x=2x+1
=>2x+1=x-1
=>x=-2(loại)
Trường hợp 3: x>=2
Pt sẽ là x-2+2x-3=2x+1
=>3x-5=2x+1
hay x=6(nhận)