Помогите срочно номер 3

Question

Помогите срочно номер 3

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Answer 1

B4=b1*q³
s5=b1(q⁴-1)/(q-1)

b4=22*(1/2)³=22*1/8=22/8=11/4=2,75

S5=22*((1/2)⁴-1)/(1/2-1) = 22*(1/16-1)/(-1/2) = 22*(-15/16)*(-2)=11*15/4=165/4=41,25

b4=(2/3)*3³=(2/3)*27=2*9=18

s5=(2/3)*(3⁴-1)/(3-1) = 2/3*(81-1)/2 = 2/3*40=80/3=26.2/3