2-sin75=2-sin(45+30)=2-sin45cos30-sin30cos45=2-√2/2*√3/2-1/2*√2/2=
=2-√6/4-√2/4=(8-√6-√2)/4
держи
2) 3cosx-5=0; 3cosx=5; cosx=5/3; x>1 => нет корней.
2п/3 ∉ [п,2п]
4п/3 ∈ [п,2п]
Ответ:
87*43 + 87^2 - 43^2/44 = 87*(43+87) - (44-1)^2/44 = 87*130 - (44^2 - 2*44 + 1)/44 =
87*130 - 44 + 2 - 1/44 = 11310 - 42 - 1/44 = 11268 - 1/44 = 11267_43/44
1.
d = -1/6 : (-1/3) = 1/2
-1/3 * (1/2 )⁵ = 3/6 = - 1/3* 1/32 = - 1/96
ОТвет: 3
2.
b₆ = b₁*q⁵ = 32
b₃ = b₁*q² = 4
32:4 = q⁵⁻² = q³ = 8
q = 2
b₁ = 4:q² = 4:4 = 1
Ответ: 1
3.
b₄ = b₁*q³
q³ = b₄ : b₁ = 8 : 1 = 8 = 2³
q = 2
S = b₁(qⁿ - 1)/(q-1)
S = 1(2⁶ -1)/(2-1) = 2⁶ - 1 = 63
Ответ: 3
4.
b₇ = b₁*q⁶
b₃ = b₁*q²
b₇/b₃ = q⁶/q² = q⁶⁻² = q⁴
1/32 : 1/2 = 1/16
q⁴ = 1/16
q = 1/2
Ответ: 1/2
5.
b₆ - b₄ = 144 b₁q²(q³ - q) = 144
b₅ - b₃ = 48 b₁q²(q² - 1) = 48
(q³- q)/(q²-1) = 144/48
q(q²-1)/(q²-1) = 3
q = 3
b₁ = 48/(q²(q²-1))
b₁ = 48/(9*8) = 48/72 = 2/3
Ответ: 2/3 и 3