a,

\(3-\left|\dfrac{-1}{2}\right|\\ =3-\dfrac{1}{2}\\ =\dfrac{6}{2}-\dfrac{1}{2}\\ =\dfrac{5}{2}\)

b,

\(\left|\dfrac{-1}{4}\right|+\dfrac{3}{4}-\left|-1\right|\\ =\dfrac{1}{4}+\dfrac{3}{4}-1\\ =1-1\\ =0\)

c,

\(\left|0,25\right|=-\left(-0,25\right)\\ 0,25=0,25\)

a ) $3-\left|\frac{-1}{2}\right|$

= 3 - \(\dfrac{1}{2}\)

= \(\dfrac{6}{2}\)- \(\dfrac{1}{2}\)= \(\dfrac{5}{2}\).

b ) $\left|\frac{-1}{4}\right|+\frac{3}{4}-|-1|$

= \(\dfrac{1}{4}\)+ \(\dfrac{3}{4}\) - 1.

= 1 - 1= 0.

c )$\left|0,25\right|=-\left(-0,25\right)$

=> 0,25 = 0,25.

a, = \(\sqrt{2}\)/2 - 1/2 = \(\sqrt{2}-1\)/2

b, = 0,5 . 10 - 1/2 = 5 - 1/2 =9/2

Đáp án là: 

a) = \(\frac{-1+\sqrt{2}}{2}\) .

b) = \(\frac{9}{2}\) .

Thực hiện phép tính

a) \(1-\dfrac{1}{2}:\dfrac{-3}{2}+\dfrac{2}{3}=1-\dfrac{1}{2}.\dfrac{2}{-3}+\dfrac{2}{3}=\)

\(=1+\dfrac{1}{3}+\dfrac{2}{3}=\dfrac{3+1+2}{3}=\dfrac{6}{3}=2\)

b) \(\dfrac{-3}{4}-\dfrac{-7}{2}+\dfrac{2}{-3}=\dfrac{-3}{4}+\dfrac{7}{2}+\dfrac{-2}{3}=\)

\(=\dfrac{-9+42-8}{12}=\dfrac{25}{12}\)

c) \(0,25-3\dfrac{1}{2}:\dfrac{1}{2}+\dfrac{-3}{4}.\dfrac{2}{-3}=0,25-\dfrac{7}{2}.2+\dfrac{1}{2}=\)

\(=0,25-7+0,5=-\dfrac{25}{4}\)

mình làm lại câu b) nha

b) |x-3|=-4

th1: x-3=-4

x=3+(-4)

x=-1

th2: x-3=4

x=3+4

x=7

b) \(\left|x-3\right|=-4\)

t/h1:\(x-3=-4\)

\(x=3-\left(-4\right)\)

\(x=7\)

t/h2:\(x-3=4\)

\(x=3-4\)

\(x=-1\)

a)TH1 x>=3 \(\left|x-3\right|\)=x-3

pttt: x-3-2x=1 suy ra x=-4 <3 -> loại

TH2 x=< 3 pttt 3-x-2x=1 suy ra x =2/3 thỏa mãn

b) VT=\(\dfrac{4^{x+2}+4^{x+1}+4^x}{21}=\dfrac{4^x\left(4^2+4+1\right)}{21}=4^x\)

VP= \(\dfrac{3^{2x}+3^{2x+1}+3^{2x+3}}{31}=\dfrac{9^x\left(1+3+27\right)}{31}=9^x\)

vậy pt đã cho tương đương với 4^x=9^x ^{\(\Leftrightarrow\left(\dfrac{4}{9}\right)\)}^x =1 suy ra x =0

bạn ơi: pttt, vt, vp là j vậy???

a) \(\left(0,25+\frac{3}{4}:1,25+1\frac{1}{3}:2\right)\)\(=\left(\frac{1}{4}+\frac{3}{4}\right):\frac{5}{4}+\frac{4}{3}:2\)\(=\frac{4}{5}+\frac{2}{3}=\frac{22}{15}\)

b) \(2^3+3\left(\frac{-3}{2}\right)^0.\left(\frac{1}{2}\right)^2.4+\left[\left(-2\right)^2:\frac{1}{2}\right]:8\)\(=8+3.1.\frac{1}{4}.4+\left[4:\frac{1}{2}\right]:8\)

\(=8+3+8:8=\frac{19}{8}\)

a: =>|x-1/4|=3/4

=>x-1/4=3/4 hoặc x-1/4=-3/4

=>x=1 hoặc x=-1/2

b: \(\left|x+\dfrac{1}{2}\right|=\dfrac{1}{2}-\dfrac{9}{4}=\dfrac{2-9}{4}=-\dfrac{7}{4}\)(vô lý)

c: \(\Leftrightarrow\left[{}\begin{matrix}2x+5=1-x\\2x+5=x-1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}3x=-4\\x=-6\end{matrix}\right.\Leftrightarrow x\in\left\{-\dfrac{4}{3};-6\right\}\)

e: =>|3/2-x|=0

=>3/2-x=0

hay x=3/2

a. \(x=\dfrac{-2}{15}-\dfrac{3}{10}\)

\(x=\dfrac{-13}{30}\)

b. \(\dfrac{-11}{12}x+\dfrac{1}{4}=\dfrac{5}{6}\)

\(\dfrac{-11}{12}x=\dfrac{5}{6}-\dfrac{1}{4}\)

\(\dfrac{-11}{12}x=\dfrac{7}{12}\)

\(x=\dfrac{7}{12}:\dfrac{-11}{12}\)

\(x=\dfrac{-7}{11}\)

c:=>2003x+2005003=2004

=>2003x=-2002999

hay \(x\in\varnothing\)