a. 4 - 2(x + 1) = 2

<=> 4 - 2x - 2 = 2

<=> -2x = 2 + 2 - 4

<=> -2x = 0

<=> x = 0

2x-1=4

2x-5=4

2x=4+1

2x=4+5

2x=5

2x=9

x=5/2

x=9/2

x=2.5

x=4.5

\(\left|2x-1\right|+\left|2x-5\right|=4\)

\(\Leftrightarrow\left|2x-1\right|+\left|5-2x\right|=4\)

Ta có: \(\hept{\begin{cases}\left|2x-1\right|\ge2x-1\forall x\\\left|5-2x\right|\ge5-2x\forall x\end{cases}}\)

\(\Rightarrow\left|2x-1\right|+\left|2x-5\right|\ge\left(2x-1\right)+\left(5-2x\right)=2x-1+5-2x=4\)

Mà \(\left|2x-1\right|+\left|2x-5\right|=4\)

\(\Rightarrow\hept{\begin{cases}\left|2x-1\right|=2x-1\\\left|5-2x\right|=5-2x\end{cases}\Leftrightarrow\hept{\begin{cases}2x-1\ge0\\5-2x\ge0\end{cases}\Leftrightarrow}\hept{\begin{cases}x\ge\frac{1}{2}\\x\le\frac{5}{2}\end{cases}\Rightarrow}\frac{1}{2}\le x\le\frac{5}{2}}\)

Vậy \(\frac{1}{2}\le x\le\frac{5}{2}\)

Tham khảo nhé~

a]={23;24;25;26....;35}

b]={4;8;14;...}

c]{4}

Tim x thuoc N=thi ko biet nha!

a)\(\frac{1}{4}+\frac{1}{3}:2x=-5\)

   \(\frac{1}{3}:2x=-5-\frac{1}{4}\)

   \(\frac{1}{3}:2x=-\frac{21}{3}\)

   \(2x=\frac{1}{3}:\left(\frac{-21}{3}\right)\)

   \(2x=-\frac{1}{21}\)

   \(x=\frac{-1}{42}\)

b)\(\left(3x-\frac{1}{4}\right).\left(x+\frac{1}{2}\right)=0\)

\(\Rightarrow\left[\begin{array}{nghiempt}3x-\frac{1}{4}=0\\x+\frac{1}{2}=0\end{array}\right.\)\(\Rightarrow\left[\begin{array}{nghiempt}3x=\frac{1}{4}\\x=-\frac{1}{2}\end{array}\right.\)\(\Rightarrow\left[\begin{array}{nghiempt}x=\frac{1}{12}\\x=-\frac{1}{2}\end{array}\right.\)

c)\(\left(2x-5\right).\left(\frac{3}{2}x+9\right).\left(0,3x-12\right)=0\)

   \(\Rightarrow\left[\begin{array}{nghiempt}2x-5=0\\\frac{3}{2}x+9=0\\0,3x-12=0\end{array}\right.\)\(\Rightarrow\left[\begin{array}{nghiempt}2x=5\\\frac{3}{2}x=-9\\0,3x=12\end{array}\right.\)\(\Rightarrow\left[\begin{array}{nghiempt}x=\frac{5}{2}\\x=-6\\x=40\end{array}\right.\)

a) 1/4 + 1/3 : 2x = -5

=> 1/3 : 2x = -5 - 1/4

=> 1/3 : 2x = -21/4

=> 2x = 1/3 : (-21/4) = -4/63

=> x = -4/63 : 2 = -2/63

Sửa đề : a) Tìm GTNN A

a) \(A=\left|x-5\right|+3\)có : \(\left|x-5\right|\ge0\Rightarrow\left|x-5\right|+3\ge0\)

\(\Leftrightarrow A\ge3\)dấu "=" xảy ra khi : \(\left|x-5\right|=0\Leftrightarrow x-5=0\Leftrightarrow x=5\)

Vậy GTNN A = 3 khi x = 5.

b) \(C=-\left|x+1\right|+5\)có : \(-\left|x+1\right|\le0\Rightarrow-\left|x+1\right|+5\le5\)

\(\Leftrightarrow C\le5\)dấu "=" xảy ra khi : \(-\left|x+1\right|=0\Leftrightarrow x+1=0\Leftrightarrow x=-1\)

Vậy GTLN C = 5 khi x = -1.

\(D=5-\left|2x+3\right|\)có : \(-\left|2x+3\right|\le0\Rightarrow5-\left|2x+3\right|\le5\)

\(\Leftrightarrow D\le5\)dấu "=" xảy ra khi : \(-\left|2x+3\right|=0\Leftrightarrow2x+3=0\Leftrightarrow x=-\frac{3}{2}\)

Vậy GTLN D = 5 khi x = -3/2.

c) \(\left|x-3\right|+\left|y+1\right|=0\)có \(\left|x-3\right|\ge0;\left|y+1\right|\ge0\Rightarrow\left|x-3\right|+\left|y+1\right|\ge0\)

\(\Rightarrow\hept{\begin{cases}\left|x-3\right|=0\\\left|y+1\right|=0\end{cases}}\Leftrightarrow\hept{\begin{cases}x=3\\y=-1\end{cases}}.\)

B=|2x+1|-4 

b, \(B=\left|2x+1\right|-4\) có : \(\left|2x+1\right|\ge0\)\(\Rightarrow\left|2x+1\right|-4\ge0\Rightarrow A\ge4\)

Dấu " = " xảy ra khi : \(\left|2x+1\right|=0\Rightarrow2x+1=0\Rightarrow2x=-1\Leftrightarrow x=-\frac{1}{2}\)

Vậy giá trị nhỏ nhất của B là 4 khi x = -1/2

a. \(\frac{3}{4}x-\frac{4}{5}.x=\frac{-2}{3}\)

\(\left(\frac{3}{4}-\frac{4}{5}\right)\) \(.x\) = \(\frac{-2}{3}\)

\(\frac{-1}{20}.x=\frac{-2}{3}\)

\(x=\frac{-2}{3}:\frac{-1}{20}\)

x =\(\frac{-40}{3}\)

a) \(\frac{3}{4}.x\) - \(\frac{4}{5}.x\) = \(\frac{-2}{3}\)

=> \(x.\left(\frac{3}{4}-\frac{4}{5}\right)\) = \(\frac{-2}{3}\)

=> \(x.\frac{-1}{20}\) = \(\frac{-2}{3}\)

=> \(x=\frac{-2}{3}:\frac{-1}{20}\)

=> \(x=\frac{40}{3}\)

(2x + 1) + (2x + 2) + ... + (2x + 2015) = 0

=> 2015.2x + (1 + 2 + 3 + ... + 2015) = 0

=> 4030x + (2015 + 1).2015 : 2 = 0

=> 4030x = -2031120

=> x = -504

x=-504

ủng hộ mk nha các bạn