某数的三分之二比它的倒数小五

1/x - 2x/3 = 5
1 - 2x²/3 = 5x
2x² + 15x - 3 = 0
x² + 15x/2 - 3/2 = 0
x² + 15x/2 + 225/16 = 249/16
(x + 15/4)² = 249/16
x + 15/4 = ±√249 / 4
x = - (15 ±√249) / 4