\(13,5.1,3+1,7x=24,35\)

\(\Rightarrow17,55+1,7x=24,35\)

\(\Rightarrow1,7x=24,35-17,55\)

\(\Rightarrow1,7x=6,8\)

\(\Rightarrow x=\frac{6,8}{1,7}\)

\(\Rightarrow x=4\)

Vậy x =4.

Cả ơn bạn nhé

k tớ trc ik tớ lm cho *hỳ hỳ*

\(\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{x.\left(x+1\right)}=\frac{4}{15}\)( đã sửa đề từ x+(x+1) thành x.(x+1) )

\(\Rightarrow\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{x}-\frac{1}{x+1}=\frac{4}{15}\)( Áp dụng \(\frac{1}{a.\left(a+1\right)}=\frac{1}{a}-\frac{1}{a+1}\))

\(\Rightarrow\frac{1}{3}-\frac{1}{x+1}=\frac{4}{15}\)

\(\Rightarrow\frac{x+1-3}{3.\left(x+1\right)}=\frac{4}{15}\)

\(\Rightarrow\frac{x-2}{3x+3}=\frac{4}{15}\)

\(\Rightarrow4.\left(3x+3\right)=15.\left(x-2\right)\)

\(\Rightarrow12x+12=15x-30\)

\(\Rightarrow12x=15x-30-12\)

\(\Rightarrow12x-15x=-30-12\)

\(\Rightarrow-3x=-42\)

\(\Rightarrow x=14\)

x . 14 + x . 15 = 292929

x . ( 14 + 15 ) = 292929

x . 29 = 292929

x = 292929 : 29

x = 10 101

\(x.14+x.15=292929\)

\(\Rightarrow x.\left(14+15\right)=292929\)

\(\Rightarrow x.29=292929\)

\(\Rightarrow x=292929:29\)

\(\Rightarrow x=10101\)

Vậy \(x=10101\)

~ Ủng hộ nha 

Giải câu b thôi nha, câu a ko hiểu * là gì hết nên ko làm đc.

(x+1)+(x+4)+(x+7)+...+(x+28)=156   (có 10 số hạng)

(x+x+x+...+x)+(1+4+7+...+28)=156

10.x+145=156

10.x=11

=>x=11/10

Noi k la fai k nha!

\(5.x+x=15:3+13\\ \Rightarrow\left(5+1\right).x=5+13=18\\ \Rightarrow6x=18\\ \Rightarrow x=\dfrac{18}{6}=3\)

\(\dfrac{2}{3}x+\dfrac{1}{3}x+\dfrac{1}{2}=\dfrac{2}{3}\\ \Rightarrow x\left(\dfrac{2}{3}+\dfrac{1}{3}\right)=\dfrac{2}{3}-\dfrac{1}{2}\\ \Rightarrow x=\dfrac{4}{6}-\dfrac{3}{6}=\dfrac{1}{6}\)

\(\dfrac{2}{5}x+x=\dfrac{3}{2}\\ \Rightarrow x\left(\dfrac{2}{5}+1\right)=\dfrac{3}{2}\\ \Rightarrow x\left(\dfrac{2}{5}+\dfrac{5}{5}\right)=\dfrac{3}{2}\\ \Rightarrow x.\dfrac{7}{5}=\dfrac{3}{2}\\ \Rightarrow x=\dfrac{3}{2}:\dfrac{7}{5}\\ \Rightarrow x=\dfrac{3.5}{7.2}=\dfrac{15}{14}\)

\(5\cdot x+x=15:3+13\)

\(\Rightarrow x\cdot\left(5+1\right)=5+13\)

\(\Rightarrow x\cdot6=18\)

\(\Rightarrow x=\dfrac{18}{6}=3\)

================

\(\dfrac{2}{3}\cdot x+\dfrac{1}{3}\cdot x+\dfrac{1}{2}=\dfrac{2}{3}\)

\(\Rightarrow x\cdot\left(\dfrac{2}{3}+\dfrac{1}{3}\right)=\dfrac{2}{3}-\dfrac{1}{2}\)

\(\Rightarrow x\cdot1=\dfrac{1}{6}\)

\(\Rightarrow x=\dfrac{1}{6}\)

=============

\(\dfrac{2}{5}\cdot x+x=\dfrac{3}{2}\)

\(\Rightarrow x\cdot\left(\dfrac{2}{5}+1\right)=\dfrac{3}{2}\)

\(\Rightarrow x\cdot\dfrac{7}{5}=\dfrac{3}{2}\)

\(\Rightarrow x=\dfrac{3}{2}:\dfrac{7}{5}\)

\(\Rightarrow x=\dfrac{15}{14}\)

X-16=18X18=324

X=324-16=308

=30

=150

tk mình nha

1+1+1+2+2+2+3+3+3+4+4+4= 1x3 + 2x3 + 3x3 + 4x4 = ,1+6+9+16= 32

1x6x5x5=6x25= 150

\(23\left(x-1\right)+19=65\)

           \(23\left(x-1\right)=65-19\)

           \(23\left(x-1\right)=46\)

                    \(x-1=46:23\)

                    \(x-1=2\)

                            \(x=2+1\)

                           \(x=3\) 

     \(5x+3x=88\)

  \(x\left(5+3\right)=88\)

         \(x.8=88\)

            \(x=88:8\)  

            \(x=11\)

\(x^3=64\)

\(x^3=4^3\)

\(\Rightarrow x=4\)

    \(\left(5x-4\right):7-2=6\)

            \(\left(5x-4\right):7=6+2\)

             \(\left(5x-4\right):7=8\)

                      \(5x-4=8.7\)

                       \(5x-4=56\)

                                \(5x=56+4\) 

                                 \(5x=60\)

                                    \(x=60:5\)

                                    \(x=12\)

\(x^{50}=x\)

\(\Rightarrow x=1\)

\(4.2^x-3=125\)

        \(4.2^x=125+3\)

        \(4.2^x=128\)

            \(2^x=128:4\)

            \(2^x=32\)

            \(2^x=2^5\)

\(\Rightarrow x=5\)

k mk nha