Question

2×2x×20+2×3x×30-4×2x×3x=20×30×1/3解是多少?

Answer 1

2×2x×20+2×3x×30-4×2x×3x=20×30×1/3

80x+180x-24x^2=200

260x-24x^2=200

24x^2-260x+200=0

6x^2-65x+50=0

△=65*65-4*6*50=4225-1200=3025

x1=(65+55)/12=120/12=10

x2=(65-55)/12=10/12=5/6