\(\frac{x-1}{x+5}\)=\(\frac{6}{7}\)...">
K
Khách

Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.

11 tháng 7 2019

a) \(\frac{x-1}{x+5}=\frac{6}{7}\)

\(\Rightarrow7.\left(x-1\right)=6.\left(x+5\right)\)

\(\Rightarrow7x-7=6x+30\)

\(\Rightarrow7x-6x=7+30\)

\(\Rightarrow x=37\)

b) \(\frac{x^2}{6}=\frac{24}{25}\)

\(\Rightarrow25.x^2=24.6\)

\(\Rightarrow25.x^2=144\)

\(\Rightarrow x^2=144:25\)

\(\Rightarrow x^2=\frac{144}{25}\)

\(\Rightarrow x^2=\frac{12^2}{5^2}\)

\(\Rightarrow x^2=\frac{12}{5}^2\)

\(\Rightarrow x=\pm\frac{12}{5}\)

11 tháng 7 2019

\(c,\frac{x-2}{x-1}=\frac{x+4}{x+7}\)

\(\Leftrightarrow(x-2)(x+7)=(x+4)(x-1)\)

\(\Leftrightarrow x^2+5x-14=x^2+3x-4\)

\(\Leftrightarrow x^2+5x-14-x^2+3x=-4\)

\(\Leftrightarrow\left[x^2-x^2\right]+5x-3x-14=-4\)

\(\Leftrightarrow2x-14=-4\)

\(\Leftrightarrow2x=10\Leftrightarrow x=5\)

28 tháng 6 2019

\(a,\frac{3x+2}{5x+7}=\frac{3x-1}{5x-1}=\frac{\left(3x+2\right)-\left(3x-1\right)}{\left(5x+7\right)-\left(5x-1\right)}=\frac{3}{8};\frac{3x+2}{5x+7}=\frac{3}{8}\Leftrightarrow24x+16=15x+21\Leftrightarrow9x=5\Leftrightarrow x=\frac{5}{9}\) \(b,\frac{37-x}{x+13}=\frac{3}{7}\Leftrightarrow37.7-7x=3x+39\Leftrightarrow259-7x=3x+39\Leftrightarrow220-7x=3x\Leftrightarrow10x=220\Leftrightarrow x=22\) \(c,\frac{x+1}{2x+1}=\frac{0,5x+2}{x+3}=\frac{x+4}{2x+6}=\frac{\left(x+4\right)-\left(x+1\right)}{2x+6-\left(2x+1\right)}=\frac{3}{5};\frac{x+1}{2x+1}=\frac{3}{5}\Leftrightarrow5x+5=6x+3\Leftrightarrow x=2\) \(d,\frac{x-2}{x+2}=\frac{x+3}{x-4}=\frac{\left(x+3\right)-\left(x-2\right)}{\left(x-4\right)-\left(x+2\right)}=\frac{5}{-6};\frac{x-2}{x+2}=\frac{5}{-6}\Leftrightarrow6\left(2-x\right)=5x+10\Leftrightarrow2-6x=5x\Leftrightarrow x=\frac{2}{11}\) \(f,\frac{3x-5}{x}=\frac{9x}{3x+2}=\frac{9x-15}{3x}=\frac{9x-\left(9x-15\right)}{\left(3x+2\right)-3x}=\frac{15}{2};\frac{9x}{3x+2}=\frac{15}{2}\Leftrightarrow18x=45x+30\Leftrightarrow27x+30=0\Leftrightarrow x=\frac{-10}{9}\) \(e,\frac{x+2}{6}=\frac{5x-1}{5}\Leftrightarrow5\left(x+2\right)=6\left(5x-1\right)\Leftrightarrow5x+10=30x-6\Leftrightarrow10=25x-6\Leftrightarrow25x=16\Leftrightarrow x=\frac{16}{25}\)

28 tháng 10 2020

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

29 tháng 10 2017

a) \(\frac{x-2}{5}=\frac{3}{8}\)

(x-2).8=5.3

(x-2).8=15

x-2=15:8

x-2=\(\frac{15}{8}\)

x=\(\frac{15}{8}+2\)

x=\(\frac{31}{8}\)

b)\(\frac{x-1}{x+5}=\frac{6}{7}\)

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

7x-7=6x+30

7x=6x+30+7

7x=6x+37

7x-6x=37

x=37

c)\(\frac{x^2}{6}=\frac{24}{25}\)

\(x^2.25=6.24\)

\(x^2.25=144\)

\(x^2=144:25\)

\(x^2=\frac{144}{25}\)

\(x^2=\left(\frac{12}{5}\right)^2\)

\(x=\frac{12}{5}\)

29 tháng 10 2017

\(\frac{x-2}{5}=\frac{3}{8}\)=>\(x-2=\frac{15}{8}\)

                           =>\(x=\frac{31}{8}\)

\(\frac{x^2}{6}=\frac{24}{25}\Rightarrow\)x2\(\frac{144}{25}\)

                      => x = \(\frac{12}{5}\)