80/x+220/(x+15)=6
问题描述:
80/x+220/(x+15)=6
答
80/x+220/(x+15)=6
40(x+15)+110x=3x(x+15)
40x+600+110x=3x²+45x
3x²-105x-600=0
x=(105±135)/6
x1=40
x2=-5