Геометрический прогресс a) b1+b2+b3=42 log2b1+log2b2+log2b3=9 Найти bn=? б)Геом...

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Геометрический прогресс
a) b1+b2+b3=42
log2b1+log2b2+log2b3=9
Найти bn=?
б)Геометрический прогресс
Sn=2+3+5+9+…+(2^n-1+1)
Найти сумму

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arsenlevadniy

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$\left\{\begin{array}{c}b_1+b_2+b_3=42,\\ \log_2b_1+\log_2b_2+\log_2b_3=9,\\b_2^2=b_1\cdot b_3;\end{array}\right. \left\{\begin{array}{c}b_1+b_2+b_3=42,\\ \log_2b_1\cdot b_2\cdot b_3=\log_22^9,\\b_2^2=b_1b_3;\end{array}\right. \\ \left\{\begin{array}{c}b_1+b_2+b_3=42,\\ b_1b_2b_3=512,\\b_2^2=b_1\cdot b_3;\end{array}\right. \left\{\begin{array}{c}b_1+b_2+b_3=42,\\ b_1b_3=\frac{512}{b_2},\\b_2^3=512;\end{array}\right.$
$\left\{\begin{array}{c} b_2=8, \\ b_1+b_3=34,\\ b_1b_3=64;\end{array}\right. \left\{\begin{array}{c} b_2=8, \\ b_3=34-b_1,\\ b_1^2-34b_1+64=0;\end{array}\right.\left\{\begin{array}{c} b_2=8, \\ b_3=34-b_1,\\ \left [ {{b_1=2} \atop {b_1=32;}} \right. \end{array}\right. \\ \left [ {{ \left\{\begin{array}{c} b_1=2, \\ b_2=8,\\ b_3=32;\end{array}\right.} \atop {\left\{\begin{array}{c} b_1=32, \\ b_2=8,\\ b_3=2.\end{array}\right.}} \right.$

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