b1=?
b4=36
b7=-32/3
b4=b1*q^3=36
b7=b1*q^6=-32/3
36/q^3=-32/3q^6
108q^6= -32q^3
108q^3=-32
q^3=-32/108
q= -8/27
q=-2/3
b1=36/(-2/3)^3= 36/ -8/27= -121.5
проверим
b7= -121.5* (-2/3)^6 =-32/3
ответ b1= -121.5
b1=?
b4=36
b7=-32/3
b4=b1*q^3=36
b7=b1*q^6=-32/3
36/q^3=-32/3q^6
108q^6= -32q^3
108q^3=-32
q^3=-32/108
q= -8/27
q=-2/3
b1=36/(-2/3)^3= 36/ -8/27= -121.5
проверим
b7= -121.5* (-2/3)^6 =-32/3
ответ b1= -121.5