b5-b3=36
b7+b7=240
надо найти b1-?
q-?
b4-b2=?

b5=b1*q^4b3=b1*q^2b7=b1*q^6составляем систему:b1*q^4-b1*q^2=36b1*q^6+b1*q^4=240;q^2=tb1*t^2-b1*t=36b1*t^3+b1*t^2=240b1(t^2-t)=36b1(t^3+t^2)=240b1=36/(t^2-t)36t^3+36t^2/t^2-t=24036t^3+36t^2=240t^2-240t3t^2-3t=20t-203t^2-17t+20=0;D=49;t=17+7/6=24/6=4t2=10/6=5/3 - не подх;q^2=4; q=2 q=-2 - не подх;b1=36/12=3b4=3*2^3=24b2=6;24-6=18Ответ: q=2 и b1=3; b4-b2=18