50x+30x+30x-2x²=50×30-1445.5
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![50x+30x+30x-2x²=50×30-1445.5](/uploads/image/z/1271749-13-9.jpg?t=50x%2B30x%2B30x-2x%26%23178%3B%3D50%C3%9730-1445.5)
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