a)\(\frac{x+1}{3}=\frac{2}{6}\)
=> \(\frac{x+1}{3}=\frac{1}{3}\)
=> x + 1 = 1 => x = 0
b) \(\frac{4-x}{-5}=\frac{-5}{4-x}\)
=> (4 - x)2 = 25
=> (4 - x)2 = 52
=> 4 - x = 5 hoặc 4 - x = -5
=> x = -1 hoặc x = 9
c) \(\frac{3}{x+2}=\frac{5}{2x+1}\)
=> 3(2x + 1) = 5(x + 2)
=> 6x + 3 = 5x + 10
=> 6x + 3 - 5x - 10 = 0
=> 6x - 5x + 3 - 10 = 0
=> 6x - 5x = 7
=> x = 7
d) \(\frac{1}{2}=\frac{x+1}{3x}\)
=> 3x = 2(x + 1)
=> 3x = 2x + 2
=> 3x - 2x - 2 = 0
=> x - 2 = 0
=> x = 2
e) \(\frac{-3}{x+1}=\frac{4}{\left(2-2x\right)}\)
=> -3(2 - 2x) = 4(x + 1)
=> -6 + 6x = 4x + 4
=> -6 + 6x - 4x - 4 = 0
=> -10 + 2x = 0
=> 2x = 10
=> x = 5