Question

Tìm \(x\) biết:

a) \(1\dfrac45:\dfrac85=0,25:x\);                                             b) \(\dfrac{2x+3}{6}=\dfrac{3x-1}{8}.\)

Answer 1

`a, 1 4/5 : 8/5 = 0,25 : x`

`=> (9/5)/(8/5) = (1/4)/x`

`=> 9/5x = 1/4 . 8/5`

`=> 9/5x = 2/5`

`=> x = 2/5 : 9/5`

`=> x=2/9`

Vậy: `x=2/9`

`b, (2x+3)/6=(3x-1)/8`

`=> (2x+3) . 8 = (3x-1) . 6`

`=> 16x + 24 = 18x - 6`

`=> 16x - 18x = -6 - 24`

`=> -2x = -30`

`=> x=15`

Vậy: `x=15`