Найдите сумму первых 5 членов прогрессии: 1)b1=8, q=1/2 2)3; -6; 3)-32; 16; )c1=-4; q=3 5)u1=3; q=2

1)
Sn=b₁*(1-qⁿ)/(1-q)
b₁=8     q=1/2  n=5
S₅=8*(1-(1/2)⁵)/ (1-1/2)=2³*(1-(1/2⁵)/(1/2)=(2³-2³/2⁵)*2=(2³-2⁻²)*2=
=2⁴-2⁻¹=32-1/2=31,5.
2)
a₁=3    a₂=-6  
q=-6/3=-2
S₅=3*(1-(-2)⁵)/(1-(-2))=3*(1+32)/3==33.
3)
-32; 16;      q=16/(-32)=-1/2
S₅=(-32*(1-(-1/2)⁵)/(1-(-1/2))=-32*(1+1/32)/(3/2)=-32*(1+1/32))*2/3=
=-4*33*2/(32*3)=-22.
4)
c₁=-4     q=3
S₅=4*(1-3⁵)/(1-3)=-4*(1-243)/(-2)=-4*(-242)/(-2)=-484.
5)u₁=3     q=2
S₅=3*(1-2⁵)/(1-2)=3*(1-32)/(-1)=3*(-31)/(-1)=93.