B₁=4 q=2 b₃-?
b₃=b₁q²=4*2²=4*4=16
Ответ: b₃=16.
18) f '(x) = (-2)' * ctgx - (-2)* (ctgx)' = 0 * ctgx + 2 * (- 1/Sin²x) = - 2/Sin²x
19) f ' (x) = (Sin15x)' = Cos15x * (15x)' = 15Cos15x
20) f '(x) = [Cos(π/4 - 12x)] ' = - Sin(π/4 - 12x) * (π/4 - 12x)' = 12Sin(π/4 - 12x)
0,1х=2,3-1,2
0,1х=1,1
х=1,1/0,1
х=11