50x+30x+30x-2x²=50×30-1445.5

50x+30x+30x-2x²=50×30-1445.5
50x+30x+30x-2x²=50×30-1445.5

50x+30x+30x-2x²=50×30-1445.5
50x+30x+30x-2x²=50×30-1445.5
2x²－110x＋54.5＝0
4x²－220x＋109＝0
（2x－109）（2x－1）＝0
2x－109＝0
x＝109/2
x₁＝54.5
2x－1＝0
x₂＝1/2

50x+30x+30x-2x²=50×30-1445.5
110x-2x²=1500-1445.5
110x-2x²=54.5
2x²-110x+54.5=0
x²-55x+27.25=0
(x-27.5)²-756.25+27.25=0
(x-27.5)²-729=0
(x-27.5)²=729
x-27.5=±27
x=27.5±27
x=0.5或x=54.5