Tg(2x-10°)=1/√3
2x-10°=30°
2x=30°+10°
2x=40°
x=20°
(у+3)²=(у+3)(у+3)=у²+3у+3у+9=у²+6у+9
bn = b1 * q^(n-1)
b6 = b1 * q^5 = 2 * 3^5 = 2 * 243 = 486
b4 = b1 * q^3 = 128 * (1/64) = 2
b9 = b1 * q^8 = 16 * (-1/2)^8 = 16 * 1/256 = 1/16
решение во вложении
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