Ответы и объяснения

2014-03-13T20:09:46+04:00
2014-03-13T20:10:05+04:00
A1=0.8 d=1.2 -------- {a11=a1+10×d {a7=a1+6×d {12.8=a1+10×d {8=a1+6×d a1=8-6×d 12.8=8-6×d+10×d 4d=4.8 d=1.2 a1=8-6×1.2 a1=0.8