3; -6; 12...
b₁=3
b₂=-6
b₃=12
q=-6/3=12/-6=-2
b₅=b₁*q⁴
b₅=3*(-2)⁴=48
S₅=(b₁ - b₅*q)/(1-q) q≠1
S₅=(3 - 48*(-2))/(1-(-2))
S₅=99/3=33
3; -6; 12...
b₁=3
b₂=-6
b₃=12
q=-6/3=12/-6=-2
b₅=b₁*q⁴
b₅=3*(-2)⁴=48
S₅=(b₁ - b₅*q)/(1-q) q≠1
S₅=(3 - 48*(-2))/(1-(-2))
S₅=99/3=33