a)x=-2/4+3/4=1/4

b)x/5=25/30+-19/30=6/30=1/5=>x=1.

THAM KHẢO NHÉ

CHÚC BN HỌC TỐT

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

b) Ta có: \(\frac{5}{6}+\frac{-19}{30}=\frac{25}{30}+\frac{-19}{30}=\frac{25-19}{30}=\frac{6}{30}=\frac{1}{5}\)

Vậy,\(\frac{x}{5}=\frac{1}{5}\)⇒\(x=1\)

\(\frac{1}{4}\cdot\frac{2}{6}\cdot\frac{3}{8}\cdot\frac{4}{10}\cdot....\cdot\frac{30}{62}\cdot\frac{31}{64}=2^x\)

\(\Leftrightarrow\frac{1}{2}\left(\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot.....\cdot\frac{30}{31}\cdot\frac{31}{32}\right)=2^x\)

\(\Leftrightarrow\frac{1}{32}=2^{x+1}\)

Làm nốt.

ko làm được câu này hay câu b ib với tớ nha.khẳng định tối giải.

a, ( 152 +và 2/4 - 148 và 3/8 ) : 0,2 = x : 0,3

=>  33/8 : 1/5 = x : 3/10

=>  x : 3/10 = 165/8

=>  x = 99/10

b, ( 85 và 7/30 - 83 và 5/18 ) : 2 và 2/3 = 0,01x : 4

=>  88/45 : 8/3 = 0,01x : 4

=> 0,01x : 4 = 11/15

=> 0,01x = 44/15

=> x = 880/3

c, x - 1/ x + 5 = 6/7

=> 7( x - 1 ) = 6( x + 5 )

=> 7x - 7 = 6x + 30

=> 7x - 6x = 7 + 30

=> x = 37

d, x²/6 = 24/25

=> x². 25 = 6 . 24

=> x².25 = 144

=> x² = 144/25

=> x = ( 12/5)² hoặc x = ( -12/5)

g, x - 3/ x + 5 = 5/7

=> 7( x - 3 ) = 5 ( x + 5 )
=> 7x - 21 = 5x + 25

=> 7x - 5x = 21 + 25

=> 2x = 46

=> x = 23

Câu b) tạm thời ko bít làm =.= 

Bài 1 : 

\(d)\) \(\frac{4^5+4^5+4^5+4^5}{3^5+3^5+3^5}.\frac{6^5+6^5+6^5+6^5+6^5+6^5}{2^5+2^5}=2x\)

\(\Leftrightarrow\)\(\frac{4^5.4}{3^5.3}.\frac{6^5.6}{2^5.2}=2x\)

\(\Leftrightarrow\)\(\frac{4^6}{3^6}.\frac{6^6}{2^6}=2x\)

\(\Leftrightarrow\)\(\frac{2^{12}}{3^6}.\frac{2^6.3^6}{2^6}=2x\)

\(\Leftrightarrow\)\(\frac{2^{12}}{3^6}.\frac{3^6}{1}=2x\)

\(\Leftrightarrow\)\(2^{12}=2x\)

\(\Leftrightarrow\)\(x=\frac{2^{12}}{2}\)

\(\Leftrightarrow\)\(x=2^{11}\)

\(\Leftrightarrow\)\(x=2048\)

Vậy \(x=2048\)

Chúc bạn học tốt ~ 

Bài 1 : 

\(a)\) Ta có : 

\(4+\frac{x}{7+y}=\frac{4}{7}\)

\(\Leftrightarrow\)\(\frac{x}{7+y}=\frac{4}{7}-4\)

\(\Leftrightarrow\)\(\frac{x}{7+y}=\frac{-24}{7}\)

\(\Leftrightarrow\)\(\frac{x}{-24}=\frac{7+y}{7}\)

Áp dụng tính chất dãy tỉ số bằng nhau ta có : 

\(\frac{x}{-24}=\frac{7+y}{7}=\frac{x+7+y}{-24+7}=\frac{22+7}{-17}=\frac{29}{-17}=\frac{-29}{17}\)

Do đó : 

\(\frac{x}{-24}=\frac{-29}{17}\)\(\Rightarrow\)\(x=\frac{-29}{17}.\left(-24\right)=\frac{696}{17}\)

\(\frac{7+y}{7}=\frac{-29}{17}\)\(\Rightarrow\)\(y=\frac{-29}{17}.7-7=\frac{-322}{17}\)

Vậy \(x=\frac{696}{17}\) và \(y=\frac{-322}{17}\)

Chúc bạn học tốt ~ 

2.

Ta có 1+2+...+n=n.(n+1):2

=>P=\(1+\frac{1}{2}.\frac{2.3}{2}+\frac{1}{3}.\frac{3.4}{2}+...+\)\(\frac{1}{16}.\frac{16.17}{2}\)=1+\(\frac{3}{2}+\frac{4}{2}+...+\frac{17}{2}\)=1+\(\frac{1}{2}.\left(3=4+..=17\right)\)

=1+\(\frac{1}{2}.153=1+\frac{153}{2}=\frac{155}{2}\)

a, X=\(\frac{1}{4}\)

a, X=\(\frac{1}{4}\)                                                                                                                                                                 

b, X=1

a) \(X=\frac{-1}{2}+\frac{3}{4}\)

 \(\Leftrightarrow X=\frac{-2}{4}+\frac{3}{4}\)

  \(\Leftrightarrow X=\frac{1}{4}\)

b) \(\frac{X}{5}=\frac{5}{6}+\frac{-19}{30}\)

  \(\Leftrightarrow\frac{X}{5}=\frac{25}{30}+\frac{-19}{30}\)

  \(\Leftrightarrow\frac{X}{5}=\frac{6}{30}=\frac{1}{5}\)

  \(\Leftrightarrow X=1\)

                             Đáp số:      a)  \(X=\frac{1}{4}\)

                                              b)   \(X=1\)

1,\(a,\frac{7}{12}+\frac{13}{32}\)

\(=\frac{56}{96}+\frac{39}{96}\)

\(=\frac{95}{96}\)

\(b,\frac{-18}{24}+\frac{25}{30}\)

\(=\frac{-3}{4}+\frac{5}{6}\)

\(=\frac{-18}{24}+\frac{20}{24}=\frac{2}{24}=\frac{1}{12}\)

2,\(a,\frac{2}{5}+\frac{-3}{7}=\frac{x}{70}\)

\(=>\frac{28}{70}-\frac{30}{70}=\frac{x}{70}\)

\(=>-\frac{2}{70}=\frac{x}{70}\)

\(=>x=-2\)

\(b,\frac{5}{6}+\frac{-19}{30}=\frac{1}{x}\)

\(=>\frac{25}{30}-\frac{19}{30}=\frac{1}{x}\)

\(=>\frac{6}{30}=\frac{1}{x}\)

\(=>\frac{1}{5}=\frac{1}{x}\)

\(=>x=5\)

1.

a) \(\frac{7}{12}+\frac{13}{32}=\frac{56}{96}+\frac{39}{96}=\frac{95}{96}\)

b) \(\frac{-18}{24}+\frac{25}{30}=\frac{-18}{24}+\frac{20}{24}=\frac{2}{24}=\frac{1}{12}\)