Tìm x:

1) \(\dfrac{1,2}{30}\)\(=\dfrac{3x+4}{50}\)

2) \(\dfrac{x-1}{x-5}\)\(=\dfrac{6}{7}\)

3) \(\dfrac{x-1}{3}\)\(=\dfrac{x+3}{5}\)

4) \(\dfrac{3}{7}\)\(=\dfrac{2x+1}{3x+5}\)

5) \(\dfrac{2x+3}{3x+1}\)\(=\dfrac{3}{4}\)

6) \(\dfrac{2x+3}{6}\)\(=\dfrac{7x-3}{15}\)

7) \(\dfrac{6x-5}{-7}\)\(=\dfrac{5x-3}{-5}\)

8) \(\dfrac{x+1}{x-2}\)\(=\dfrac{3}{4}\)

9) \(\dfrac{2x-3}{x+1}\)\(=\dfrac{4}{7}\)

10) \(\dfrac{2x+3}{7}\)\(=\dfrac{4x-1}{15}\)

11) \(\dfrac{2x+3}{24}\)\(=\dfrac{3x-1}{32}\)

12) \(\dfrac{2x+4}{7}\)\(=\dfrac{4x-2}{15}\)

13) \(\dfrac{11x-2}{7x+5}\)\(=\dfrac{11}{8}\)

14) \(\dfrac{12-7x}{-13}\)\(=\dfrac{4-3x}{-5}\)

15) \(\dfrac{52}{2x-1}\)\(=\dfrac{13}{30}\)

Tìm x biết:
a) \(\dfrac{-32}{\left(-2\right)^x}=4\) f) \(\left(3x-1\right)^3=\dfrac{-8}{27}\)

b) \(\left(\dfrac{1}{2}\right)^{2x-1}=\dfrac{1}{8}\) g) \(\left(2x+3\right)^2=\dfrac{9}{121}\)

c) \(\dfrac{1}{9}.27^x=3^x\) h) \(5^x+5^{x+2}=650\)

d) \(9^x:3^3=\dfrac{1}{243}\) i) \(\left(x-7\right)^{x+1}-\left(x-7\right)=0\)

e) \(\dfrac{x7}{81}=27\) m) \(\left(\dfrac{-3}{4}\right)^{3x-1}=\dfrac{256}{81}\)

Tìm x,y,z trong dãy tỉ số bằng nhau

1)\(\dfrac{3x}{8}=\dfrac{3y}{64}=\dfrac{3z}{216}\)và \(2x^2+2y^2.z^2=1\)

2) \(\dfrac{2x+1}{5}=\dfrac{4y-5}{9}=\dfrac{2x+4y-4}{7x}\)

3) \(\dfrac{x^3+y^3}{6}=\dfrac{x^3-2y^3}{4}\)và x⁶ . y⁶ =14

4) \(\dfrac{x+4}{6}=\dfrac{3y-1}{8}=\dfrac{3y-x-5}{x}\)

5) \(\dfrac{3}{x-1}=\dfrac{4}{y-2}=\dfrac{5}{z-3}\)và x.y.z=192

6)\(\dfrac{x-y}{3}=\dfrac{x+y}{13}=\dfrac{x.y}{200}\)

7)\(\dfrac{x+1}{2}=\dfrac{y-1}{3}=\dfrac{z+2}{4}=\dfrac{x+y+z+2}{2x+5}\)

8) \(\dfrac{15}{x-9}=\dfrac{20}{y-12}=\dfrac{40}{z-24}\)và x.y = 1200

9)\(\dfrac{40}{x-30}=\dfrac{20}{y-15}=\dfrac{28}{z-21}\) và x.y.z = 22400

10)15x = -10y =6z và x.y.z = -30000

11) Cho\(\dfrac{x+1}{3}=\dfrac{y-2}{5}=\dfrac{2z+14}{9}\)và x+z=y

12) Cho \(\dfrac{x}{3}=\dfrac{y}{4}\)và \(\dfrac{y}{5}=\dfrac{z}{6}\).Tính M=\(\dfrac{2x+3y+4z}{3x+4y+5z}\)

1. Tìm tỉ số \(\dfrac{x}{y}\) biết \(\dfrac{2x-y}{x+y}\)=\(\dfrac{2}{3}\)
2. Tìm x:
a) 3,8 : (2x) = \(\dfrac{1}{4}:2\dfrac{2}{3}\)
b) \(1\dfrac{1}{3}\) : 0,8 = \(\dfrac{2}{3}\) : (0,1x)
c) \(\dfrac{x}{-15}\) = \(\dfrac{-60}{x}\)

d) \(\dfrac{-2}{x}=\dfrac{-x}{\dfrac{8}{25}}\)

e) 0,2 : \(1\dfrac{1}{5}\)= \(\dfrac{2}{3}\) : (6x+7)
3. Tính A = \(\dfrac{8^{10}+4^{10}}{8^4+4^{11}}\)

tìm x , biết :

a, \(\dfrac{37-x}{2x+5}=\dfrac{4}{9}\)

b, \(\dfrac{x-2}{x-1}=\dfrac{x+4}{x+7}\)

c, \(\dfrac{x+3}{25}=\dfrac{9}{x+3}\)

d, \(\dfrac{x}{\dfrac{-2}{3}}=\dfrac{5}{-x}\)

e, \(\dfrac{2x-5}{\dfrac{3}{2}}=\dfrac{\dfrac{-27}{8}}{5-2x}\)

f, \(\dfrac{\dfrac{5}{9}}{\left(3x-1\right)^2}=\dfrac{1-2x}{\dfrac{25}{3}}\)

Tìm x; y biết:

a) \(\dfrac{x}{4}\)= \(\dfrac{y}{3}\)=\(\dfrac{2}{9}\) và x - 3y + 42 = 62

b) \(\dfrac{x}{y}\)=\(\dfrac{7}{9}\) và \(\dfrac{y}{z}\)= \(\dfrac{7}{3}\) và x - y + z = -15

c)\(\dfrac{x}{y}\)=\(\dfrac{7}{20}\); \(\dfrac{y}{z}\)=\(\dfrac{5}{8}\) và 2x + 5y - 2z =100

d) 5x = 8y = 20 và x-y-z = 3

e) \(\dfrac{6}{11}\) . x =\(\dfrac{2}{2}\). y =\(\dfrac{18}{5}\). z và (-x) +y + 2 = -120

f ) \(\dfrac{x}{12}\)=\(\dfrac{y}{9}\)=\(\dfrac{2}{5}\) và x . y . z =20

tìm x :

a) \(\dfrac{x+1}{7}+\dfrac{x+1}{8}=\dfrac{x+1}{9}+\dfrac{x+1}{10}\)

b) \(\dfrac{x+1}{12}+\dfrac{x^2}{11}=\dfrac{x+3}{10}+\dfrac{x+4}{9}\)

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

d)\(\dfrac{3x+2}{5x+7}=\dfrac{3x-1}{5x-3}\)

2 tìm x,y,z

a) \(\dfrac{x}{2}=\dfrac{y}{3},\dfrac{y}{4}=\dfrac{z}{5}vàx^2-y^2=-16\)

b)2x=3y,5x=7z và 3x-7y+5z=30