b1+b1*q+b1*q^2= -105
b1+b1*4+b1*4^2= -105
21b1 = -105
b1 = -5
Сумма первых пяти членов = (b1+b1*4+b1*4^2)+b1*4^3+b1*4^4 = -105 -5**4^3 -5*4^4 = -105-320-1280 = 1705
3) f(x) = 2√2*x - sin(4x)
f' = 2√2 - 4cos(4x) = 0
4cos(4x) = 2√2
cos(4x) = √2/2
4x = +-π/4 + 2πk
x = +-π/16 + πk/2
4) f' = 0.5*x^2 - x ≥ 0
x*(0.5x - 1) ≥ 0
x ≤ 0, x ≥ 2
A)5^-4*5=5^-3=1/125
Б)12^1 =12
В)3^3=27
^степень