РЕШЕНИЕ:

a_n + 1=a_n+16 ⇒ d = 16

a_n = a₁ + d(n-1)

a₁₇ = a₁ + d(n-1) = 37+ 16 (17 – 1) = 37 + 256 = 293

S₁₇ = (a₁ + a₁₇)∙17 / 2

S₁₇ = (a₁ + a₁₇)∙8.5

S₁₇ = (37 + 293)∙8.5 = 2805

Ответ: 2805

РЕШЕНИЕ:

___− 11___ ≥ 0
(x−2)²−3

(x−2)²−3 < 0

x² – 4x + 4 – 3 < 0

x² – 4x + 1 < 0

x² – 4x + 1 = 0
D = 16 – 4∙1∙1 = 16 – 4 = 12 = 3∙4 = (2√3)²

x₁ = (4 + 2√3) / 2 = 2 + √3

x₂ = ( 4 – 2√3) / 2 = 2 – √3

____ + ________ – _________ +
__________o____________o________
______ 2 – √3_____ 2 + √3

Ответ: ( 2 – √3 ; 2 + √3)

РЕШЕНИЕ:
sin²A + cos²A = 1

cos²A = 1 - sin²A = 1 - (3/20)² = 1 - 9/400 = 400/400 - 9/400 = 391/400

cosA = √(391/400) = √391 / 20

cosA = AC / AB

AB = AC / cosA = √391 : √391/20 = √391∙ 20/√391 = 20

Ответ: 20

РЕШЕНИЕ:

S = a + b ∙ h
____ 2

S = 11 + 3 ∙ 3
____ 2

S = 7 ∙ 3 = 21

Ответ: 21