(43.5²-39.5²)/(1.8²+0.72+0.2²)=(43.5-39.5)*(43.5+39.5)/(1.8+0.2)²=
4*83/2²=83*4/4=83
использовал ФСУ х²+2*х*у+у²=(х+у)²; х²-у²=(х-у)*(х+у)
(43.5²-39.5²)/(1.8²+0.72+0.2²)=(43.5-39.5)*(43.5+39.5)/(1.8+0.2)²=
4*83/2²=83*4/4=83
использовал ФСУ х²+2*х*у+у²=(х+у)²; х²-у²=(х-у)*(х+у)