a) \(\left(\frac{2}{3}\right)^x=\left(\frac{4}{9}\right)^{50}\)

\(\Rightarrow\left(\frac{2}{3}\right)^x=\left(\frac{2^2}{3^2}\right)^{50}\)

\(\Rightarrow\left(\frac{2}{3}\right)^x=\left(\frac{2}{3}\right)^{100}\)

\(\Rightarrow x=100\)

Vậy x = 100

b) \(\left(\frac{2}{3}-x\right)^2=\frac{1}{36}\)

\(\Rightarrow\left(\frac{2}{3}-x\right)^2=\left(\frac{1}{6}\right)^2\)

\(\Rightarrow\frac{2}{3}-x=\frac{1}{6}\)

\(\Rightarrow x=\frac{2}{3}-\frac{1}{6}\)

\(\Rightarrow x=\frac{1}{2}\)

Vậy \(x=\frac{1}{2}\)

2) 

Ta có:

\(74^{m+1}+74^m=74^m.74^1+74^m=74^m.\left(74+1\right)=74^m.75⋮25\)

( vì \(75⋮25\) )

\(\Rightarrowđpcm\)

giup minh vs mai minh di hoc rui

a)\(\frac{1}{2}x+\frac{9}{4}-\frac{8}{20}=\frac{77}{20}\)

<=>\(\frac{1}{2}x=\frac{77}{20}-\frac{9}{4}+\frac{8}{20}=\frac{77-45+8}{20}\)

<=>\(\frac{1}{2}x=\frac{40}{20}=2\)

<=>\(x=2:\frac{1}{2}=2.2\)

<=>x=4

                     Vậy x=4

trời ??? này mà là toán lớp 5 what???

A)2013x3,64+7,26x2013–2013x10,89

=2013x(3,64+7,26–10,89)

=2013x0,01

=20,13

B) \(3\frac{1}{4}\) giờ —1 giờ 15 phút

=\(3\frac{1}{4}\)giờ —\(1\frac{1}{4}\)giờ

= 2 giờ

a) 2013 x 3,64 + 7,26 x 2013 - 2013 x 10,89

= ( 3,64 + 7,26 -10,89 ) x 2013

= 0,01 x 2013

= 20,13.

b)\(\frac{28}{100}x+\frac{4}{25}+\frac{10}{4}=\frac{203}{50}\)

<=>\(\frac{28}{100}x=\frac{203}{50}-\frac{10}{4}-\frac{4}{25}=\frac{406-250-16}{100}\)

<=>\(\frac{28}{100}x=\frac{140}{100}\)

<=>\(x=\frac{140}{100}:\frac{28}{100}=\frac{140}{100}.\frac{100}{28}\)

<=>x=5

a) \(\frac{1}{2}x+\frac{9}{4}-\frac{8}{20}=\frac{77}{20}\)

=>  \(\frac{1}{2}x=\frac{77}{20}+\frac{8}{20}-\frac{9}{4}=2\)

=>  \(\frac{x}{2}=2\Rightarrow x=2\cdot2=4\)

vậy x = 4

b) \(\frac{28}{100}x+\frac{4}{25}+\frac{10}{4}=\frac{203}{50}\)

=>  \(\frac{28}{100}x=\frac{203}{50}-\frac{10}{4}-\frac{4}{25}=1\frac{2}{5}=\frac{7}{5}\)

=> \(\frac{28x}{100}=\frac{7}{5}\Rightarrow28x=\frac{100\cdot7}{5}=140\Rightarrow x=140:28=5\)

vậy x = 5

c)  \(\frac{100}{58}=\frac{1}{2}x\)

=>  \(\frac{100}{58}=\frac{x}{2}\Rightarrow x=\frac{100\cdot2}{58}=3\frac{13}{29}=\frac{100}{29}\)

vậy x = 100/29

Bài 2: 

a: =47,4+47,4x4=47,4x5=237

b: =(0,26+0,74)+(0,41+0,59)=1+1=2

Tính bằng cách thuận tiện ( đề `b` )

`13/50+74/100+41/100+59/100`

`=>` `26/100+74/100+41/100+59/100`

`=>` `(26/100+74/100) + ( 41/100 + 59/100)`

`=>` `1+1`

`=>` `2`