a1/a2=a2/a3=…=a5/a6=a6/a7
a1/a2*a2/a3*.*a5/a6*a6/a7=a1/a7=(a6/a7)∧6
所以:(a6)∧6=a1*(a7)∧5
因为(a5)∧3=(a6/a7)∧3*(a6)∧3=(a6)∧6/(a7)∧3
所以:(a5)∧3=a1*(a7)∧2=8*5862∧2=648∧3
a5=648
a1/a2=a2/a3=…=a5/a6=a6/a7
a1/a2*a2/a3*.*a5/a6*a6/a7=a1/a7=(a6/a7)∧6
所以:(a6)∧6=a1*(a7)∧5
因为(a5)∧3=(a6/a7)∧3*(a6)∧3=(a6)∧6/(a7)∧3
所以:(a5)∧3=a1*(a7)∧2=8*5862∧2=648∧3
a5=648