CV Crazy Vel q=-2; S5 = 5.5; b5=? решение: n=5; Sn = b1(q^n-1)/(q-1) 5.5=b1(-2^5-1)/(-2-1)=-33b1/(-3)=11b1 b1=5.5/11; b5=b1*q^(5-1)=5.5/11*(-2)^4=5.5/11*16=88/11=8