720 : ( X x5 )= 6

X x 5 = 720 : 6

X x 5 =120

X      = 120 : 5

X = 24

chúc bạn học tốt

720:(x.2+x.3)=2.3

=> 720:[x.(2+3)]=6

=> x.5              =720:6

=> x.5              =120

=> x                 =120:5

=> x                 =24

Vậy x=24

720 : ( X x 2+ X x 3)= 2x3

720 : ( X x 2+ X x 3)= 6

720 : [X x (2+3)] = 6

720 : (X x 5) = 6

720 : 5 x X = 6

X = 720 : 5 : 6 

X = 24

720 :[x +2 . x +3] =2.3

720:(x+2.x+3)=6

x+2.x+3=120

x.(2+3)=120

x.5=120

x=24

\(720:\left[X+2xX+3\right]=2x3\)

\(720:\left[x+\left(2+3\right)\right]=6\)

          \(x+5=720:6\)

           \(x+5=120\)

           \(x=120-5\)

           \(x=115\)

\(720\div\left(x\times5\right)=6\)

\(x\times5=720\div6\)

\(x\times5=120\)

\(x=120\div5\)

\(x=24\)

#TThuHuongg

\(3^{x+1}+3^{x+2}=2^2.3^4\)

\(3^{x+1}+3.3^{x+1}=4.81\)

\(4.3^{x+1}=4.81\)

\(3^{x+1}=81=3^4\)

\(x+1=4\Rightarrow x=3\)

3^x+25=26x2²+2x3⁰

3^x+25=26x4+2

3^x+25=106

3^x=106-25=81

3^x=3⁴

⇒ x=4

lê minh quang bị mắc lỗi ở chỗ 3^0

a: =>41-(2x-5)=720:40=18

=>2x-5=23

=>2x=28

=>x=14

b: =>100x+5050=5750

=>100x=700

=>x=7

a: =>41-(2x-5)=720:40=18

=>2x-5=23

=>2x=28

=>x=14

b: =>100x+5050=5750

=>100x=700

=>x=7

b) \(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{2013.2015}\)

\(=\frac{1}{2}\left(\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{2013.2015}\right)\)

\(=\frac{1}{2}\left(\frac{3-1}{1.3}+\frac{5-3}{3.5}+\frac{7-5}{5.7}+...+\frac{2015-2013}{2013.2015}\right)\)

\(=\frac{1}{2}\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{2013}-\frac{1}{2015}\right)\)

\(=\frac{1}{2}\left(1-\frac{1}{2015}\right)=\frac{1007}{2015}\)

Phương trình tương đương với: 

\(\frac{1007X}{2015}=\frac{4}{2015}\Leftrightarrow X=\frac{4}{1007}\)

c) \(\frac{x+1}{2015}+\frac{x+2}{2016}=\frac{x+3}{2017}+\frac{x+4}{2018}\)

\(\Leftrightarrow\frac{x+1}{2015}-1+\frac{x+2}{2016}-1=\frac{x+3}{2017}-1+\frac{x+4}{2018}-1\)

\(\Leftrightarrow\frac{x-2014}{2015}+\frac{x-2014}{2016}=\frac{x-2014}{2017}+\frac{x-2014}{2018}\)

\(\Leftrightarrow x-2014=0\)

\(\Leftrightarrow x=2014\)

\(720:\left[41-\left(2x-5\right)\right]=40\)                                      \(3x+8x-30=25\)

\(41-\left(2x-5\right)=18\)                                                     \(3x+8x=55\)

\(2x-5=23\)                                                                    \(11x=55\)

\(2x=28\)                                                                                  \(x=5\)

\(x=14\)