Question

Помогите с 2 заданиями

Answer 1

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Answer 2

$1) \ S = \frac{b_1}{1-q} \Rightarrow b_1 = 27(1-q) \\ \\ b_1+b_2+b_3 = 35 \\ b_1+b_1\cdot q+b_1\cdot q^2=35 \\ 27(1-q)+27(1-q) \cdot q + 27(1-q) \cdot q^2=35 \\ 27-27q+27q-27q^2+27q^2-27q^3=35 \\ 27-27q^3=35 \\ -27q^3=8 \\ q^3= -\frac{8}{27} \\ q = -\frac{2}{3} \\ b_1 = 27 \cdot \frac{5}{3} = 45 \\ \\ \\ \\ 2) \ 0,2474747... = 0,2(47) = \frac{247-2}{990} = \frac{245}{990} = \frac{49}{198}$