\(20\%\times25,5+\dfrac{1}{5}\times15,5+0,2\times59\)

\(=\dfrac{1}{5}\times25,5+\dfrac{1}{5}\times15,5+\dfrac{1}{5}\times59\)

\(=\dfrac{1}{5}\times\left(25,5+15,5+59\right)\)

\(=\dfrac{1}{5}\times100\)

\(=20\)

a) \(\dfrac{3}{4}-\dfrac{1}{2}x=-\dfrac{1}{4}\)

\(\Leftrightarrow3-2x=-1\)

\(\Leftrightarrow-2x=-1-3\)

\(\Leftrightarrow-2x=-4\)

\(\Leftrightarrow x=2\)

Vậy \(x=2\)

b) \(1\dfrac{2}{3}x+0,2=x-\dfrac{7}{8}\)

\(\Leftrightarrow\dfrac{5}{3}x+\dfrac{1}{5}=x-\dfrac{7}{8}\)

\(\Leftrightarrow200x+24=120x-105\)

\(\Leftrightarrow80x=-129\)

\(\Leftrightarrow x=-\dfrac{129}{80}\)

Vậy \(x=-\dfrac{129}{80}\)

c) \(\dfrac{3}{4}-\left|x+0,5\right|=\dfrac{1}{5}\)

\(\Leftrightarrow-\left|x+0,5\right|=\dfrac{1}{5}-\dfrac{3}{4}\)

\(\Leftrightarrow-\left|x+0,5\right|=-\dfrac{11}{20}\)

\(\Leftrightarrow\left|x+0,5\right|=\dfrac{11}{20}\)

\(\Leftrightarrow\left[{}\begin{matrix}x+0,5=\dfrac{11}{20}\\x+0,5=-\dfrac{11}{20}\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{20}\\x=-\dfrac{21}{20}\end{matrix}\right.\)

Vậy \(x_1=-\dfrac{21}{20};x_2=\dfrac{1}{20}\)

d) \(\left(x+0,2\right)^2+0,75=1\)

\(\Leftrightarrow\left(x+\dfrac{1}{5}\right)^2+\dfrac{3}{4}=1\)

\(\Leftrightarrow\left(x+\dfrac{1}{5}\right)^2=1-\dfrac{3}{4}\)

\(\Leftrightarrow\left(x+\dfrac{1}{5}\right)^2=\dfrac{1}{4}\)

\(\Leftrightarrow x+\dfrac{1}{5}=\pm\dfrac{1}{2}\)

\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{5}=\dfrac{1}{2}\\x+\dfrac{1}{5}=-\dfrac{1}{2}\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{3}{10}\\x=-\dfrac{7}{10}\end{matrix}\right.\)

Vậy \(x_1=-\dfrac{7}{10};x_2=\dfrac{3}{10}\)

a, \(\dfrac{3}{4}-\dfrac{1}{2}x=-\dfrac{1}{4}\)

=>\(-\dfrac{1}{2}x=-\dfrac{1}{4}-\dfrac{3}{4}\)

=>\(-\dfrac{1}{2}x=-1\)

=>\(x=-1:(-\dfrac{1}{2})\)

=>\(x=2\)

vậy ...........

b,\(1\dfrac{2}{3}x+0,2=x-\dfrac{7}{8}\)

=>\(\dfrac{5}{3}x+0,2=x-\dfrac{7}{8}\)

=>\(\dfrac{5}{3}x-x=-\dfrac{7}{8}-0,2\)

=>\(\dfrac{2}{3}x=-\dfrac{43}{40}\)

=>\(x=-\dfrac{43}{40}:\dfrac{2}{3}\)

=>\(x=-\dfrac{192}{80}\)

vậy...................

c,\(\dfrac{3}{4}-\left|x+0,5\right|=\dfrac{1}{5}\)

=>\(-\left|x+0,5\right|=\dfrac{1}{5}-\dfrac{3}{4}\)

=>\(-\left|x+0,5\right|=-\dfrac{11}{20}\)

=>\(\left|x+0,5\right|=\dfrac{11}{20}\)

=>\(\left[{}\begin{matrix}x+0.5=\dfrac{11}{20}\\x+0,5=-\dfrac{11}{20}\end{matrix}\right.\)

=>\(\left[{}\begin{matrix}x=\dfrac{1}{20}\\x=-\dfrac{21}{20}\end{matrix}\right.\)

vậy ....... hoặc.....

d,\((x+0,2)^2+0,75=1\)

=>\(\left(x+0,2\right)^2=1-0,75\)

=>\(\left(x+0,2\right)^2=0,25\)

=>\(\left[{}\begin{matrix}x+0,2=0,5\\x+0,2=-0,5\end{matrix}\right.\)

=>\(\left[{}\begin{matrix}x=0,3\\x=-0,7\end{matrix}\right.\)

vậy..........................

HỌC TỐT NHA !!!!!

a: x:3,2+3,6=9,6:1,2

=>x:3,2+3,6=8

=>x:3,2=8-3,6=4,4

=>\(x=4,4\cdot3,2=14,08\)

b: \(25,4+5x=313,5+4,4\)

=>\(5x+25,4=317,9\)

=>\(5x=317,9-25,4=292,5\)

=>\(x=\dfrac{292.5}{5}=58,5\)

c: \(12,5\cdot x-56,5=75,8\cdot2\)

=>\(x\cdot12,5-56,5=151,6\)

=>\(x\cdot12,5=151,6+56,5=208.1\)

=>\(x=\dfrac{208.1}{12.5}=16,648\)

d: \(3,84\cdot x-4,2=22,5:1,5\)

=>\(3,84x-4,2=15\)

=>3,84x=15+1,2=16,2

=>x=16,2/3,84=4,21875

e: 22,5*x=31,5*2,6

=>x*22,5=81,9

=>x=81,9/22,5=3,64

bạn tách ra đi bạn ơi

\(-15,5\times20,8+3,5\times9,2-15,5\times9,2+3,5\times20,8.\)

\(=20,8\times\left(3,5-15,5\right)+9,2\times\left(3,5-15,5\right)\)

\(=\left(3,5-15,5\right)\times\left(20,8+9,2\right)\)

\(=\left(-12\right)\times30\)

\(=-360\)

 -15,5 x 20,8 + 3,5 x 9,2- 15,5 x 9,2 + 3,5 x 20,8=-360

k mk nha mn 

=-360 nha pạn

câu 1. 7800

câu 2:1000

sai đề câu a rồi hay sao bạn ơi bạn thử kiểm lại đi nhé

ủa dễ mà đáp an là a 01682

a, 15,5: 0,125 + 15,5: 0,2+ 15,5:0,5 + 15,5:0,25

= 15,5 \(\times\) 8 + 15,5 \(\times\) 5 + 15,5 \(\times\) 2 + 15,5 \(\times\) 4

= 15,5 \(\times\)8 + 15,5 \(\times\) 5 + 15,5 \(\times\)2 + 15,5 \(\times\) 5 - 15,5

= 15,5 \(\times\) ( 8 + 5 + 2 + 5) - 15,5

= 15,5 \(\times\)   20 - 15,5

= 310 -15,5

= 294,5

b, 22,1 : 0,25 + 22,1 : 0,5 + 22,1 : 0,2 + 22,1: 0,125

= 22,1 \(\times\) 4 + 22,1 \(\times\)2 + 22,1 \(\times\) 5 + 22,1 \(\times\) 8

= 22,1 \(\times\) 5 - 22,1 + 22,1 \(\times\) 2 + 22,1 \(\times\) 5 + 22,1 \(\times\) 8

= 22,1 \(\times\) ( 5 + 2 + 5 + 8)  - 22,1

= 22,1 \(\times\) 20 - 22,1

= 442 - 22,1

= 419,9

a: \(12:\dfrac{3}{4}+75\%\cdot\dfrac{1}{2}-16\cdot50\%\)

\(=12\cdot\dfrac{4}{3}+\dfrac{3}{4}\cdot\dfrac{1}{2}-16\cdot0,5\)

\(=16-8+\dfrac{3}{8}\)

\(=8,375\)

b: \(75\%\cdot4+22,5:3-1\dfrac{3}{5}\)

\(=0,75\cdot4+7,5-1,6\)

\(=3+7,5-1,6\)

=10,5-1,6

=8,9

x + 15 , 5 = 25 , 5 

        x     = 25 , 5 - 15 , 5 

        x     =  10 

=10 nha