Question

1)Tìm x, biết:

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

b)\(\dfrac{2x+1}{3x-2}=\dfrac{5x+1}{9x+1}\)

2)Tìm x,y,z biết:

a)\(\dfrac{x}{2}=\dfrac{y}{3}=\dfrac{z+1}{4}\) và 2x+3y-z=11

b)\(\dfrac{2x+1}{5}=\dfrac{3y-2}{7}=\dfrac{2x+3y-1}{6x}\)

Giúp mình với mình đang cần gấp!!!THANK NHÌU

Answer 1

1) Tìm x, biết :

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

=> \(5\left(x-1\right)=3\left(x+1\right)\)

=> \(5x-5=3x+3\)

=> \(5x-5-3=3x\)

=> \(5x-8=3x\)

=> \(8=5x-3x\)

=> \(8=2x\)

=> x = 8 : 2

=> x = 4