245-5 nhan(16+x)=140

        5 nhan(16+x)=245-140

         5 nhan (16+x) = 105

                       16+x   =105:5 

                        16+x= 21

                              x=21-16

                               x=5

k cho mik nhé đúg r

Số số hạng của dãy là : \(\left(45-1\right)\div4+1=12\)( số )

Ta có :

\(\left(x+1\right)+\left(x+5\right)+\left(x+9\right)+....+\left(x+45\right)=331,2\)

\(\Leftrightarrow12\times x+\frac{\left(45+1\right)\times12}{2}=331,2\)

\(\Leftrightarrow12\times x+276=331,2\)

\(\Leftrightarrow12\times z=55,2\)

\(\Leftrightarrow x=4,6\)

Vậy \(x=4,6\)

a/\(x-\dfrac{5}{7}-\dfrac{13}{14}=1\)
\(x=1+\dfrac{5}{7}+\dfrac{13}{14}\)
\(x=\dfrac{14}{14}+\dfrac{10}{14}+\dfrac{13}{14}\)
\(x=\dfrac{37}{14}\)
Vậy \(x=\dfrac{37}{14}\)
b/\(\dfrac{3}{5}+x+1\dfrac{1}{5}=\dfrac{11}{3}\)
\(x+\dfrac{3}{5}+\dfrac{6}{5}=\dfrac{11}{3}\)
\(x+\dfrac{9}{5}=\dfrac{11}{3}\)
\(x=\dfrac{11}{3}-\dfrac{9}{5}\)
\(x=\dfrac{55}{15}-\dfrac{27}{15}\)
\(x=\dfrac{28}{15}\)
Vậy \(x=\dfrac{28}{15}\)
#kễnh

a) \(x-\dfrac{5}{7}-\dfrac{13}{14}=1\)

\(x-\dfrac{23}{14}=1\)

\(x=1+\dfrac{23}{14}\)

\(x=\dfrac{37}{14}\)

b) \(\dfrac{3}{5}+x+1\dfrac{1}{5}=\dfrac{11}{3}\)

\(x+1+\dfrac{3}{5}+\dfrac{1}{5}=\dfrac{11}{3}\)

\(x+\dfrac{9}{5}=\dfrac{11}{3}\)

\(x=\dfrac{11}{3}-\dfrac{9}{5}\)

\(x=\dfrac{28}{15}\)

a) Tìm x

\(\frac{8}{5}+x=\frac{17}{3}\)

\(\Rightarrow x=\frac{17}{3}-\frac{8}{5}\)

\(\Rightarrow x=\frac{61}{15}\)

\(x-\frac{17}{14}=\frac{80}{11}\)

\(\Rightarrow x=\frac{80}{11}+\frac{17}{14}\)

\(\Rightarrow x=\frac{1307}{154}\)

b) Tính nhanh

\(52\times95+47\times95+95\)

\(=95\times\left(52+47+1\right)\)

\(=95\times100\)

\(=9500\)

\(a.\)\(\frac{8}{5}+x=\frac{17}{3}\)

\(\Leftrightarrow x=\frac{17}{3}-\frac{8}{5}\)

\(\Leftrightarrow x=\frac{85}{15}-\frac{24}{15}\)

\(\Leftrightarrow x=\frac{61}{15}\)

\(x-\frac{17}{14}=\frac{80}{11}\)

\(\Leftrightarrow x=\frac{80}{11}+\frac{17}{14}\)

\(\Leftrightarrow x=\frac{1120}{154}+\frac{187}{154}\)

\(\Leftrightarrow x=\frac{1307}{154}\)

\(b.\)Cách tính nhanh nhé:

\(52.95+47.95+95\)

\(=52.95+47.95+95.1\)

\(=95.\left(52+47+1\right)\)

\(=95.100\)

\(=9500\)

~ Rất vui vì giúp đc bn ~

a)12 x 18 + 14 x 3 - 255 : 17=25.58823529411765

b)68 + 42 x 5 - 625 : 25=5182

c) 13+ 21 x 5 - (198 : 11 - 8)=108

d) 1188 - 4 x (27 + 90 + 73 :10 )=

e) 5 + 8 + 11 + 14 +......+ 38 + 41=

f) 51 - 49 + 55 - 53 + 59 - 56 + 63 - 61 + 65=74

có mấy câu mình ko biết,xin lỗi bạn

\(\frac{38}{11}+\frac{4}{17}-\frac{5}{11}-\frac{3}{17}\) 

\(=\frac{38}{11}-\frac{5}{11}+\frac{4}{17}-\frac{3}{17}\) 

\(=\frac{33}{11}+\frac{1}{17}\) 

\(=3+\frac{1}{17}\) 

\(=\frac{52}{17}\)

38/11+4/17-5/11-3/17

=(38/11-5/11)+(4/17-3/17)

=3+1/17

=51/17+1/17=52/17

`#25080409`

\(\dfrac{6}{11}\times\dfrac{3}{7}+\dfrac{3}{7}\times\dfrac{5}{11}?\)

`=`\(\left(\dfrac{6}{11}+\dfrac{5}{11}\right)\times\dfrac{3}{7}\)

`=`\(\dfrac{11}{11}\times\dfrac{3}{7}=1\times\dfrac{3}{7}=\dfrac{3}{7}\)

kệ

0,25 hay 0 \(\times\) 25 vậy em?

cả chỗ 0.4 và 0.75 nữa em ơi