6/x+(140-x)/16=15 x等于多少?
问题描述：
6/x+(140-x)/16=15 x等于多少?
答
(6*16+140x-x^2)/16x=15
96+140x-x^2=240x
x^2+100x-96=0
∴ x=(-100+-√100^2+4*1*96)/2
=(-100+-√10384)/2
=(-100+-√16*649)/2
=-50+-2√649 (√表示根号2)