2x^2-7x-8=0
D=49+64=113
x1= (7+√113)/4
x2= (7-√113)/4
x1+x2=-b/a=7/2=3,5
Решение:
sin4a+2sin4acos2a=sin4a(1+2cos2a)=sin4a(1+2cos^2a-2sin^2a-2+2sin^2a+2cos^2a)=
=sin4a(4cos^2a-1).
3) f(x) = (6x -1)⁻⁵
f'(x) = -5(6x -1)⁻⁶ * (6x -1)' = -30/(6x -1)⁶
f'(x₀) = f'(1/3) = -30/(6*1/3 -1)⁶ = -30
4) f(x) = √(3x² +4)
f'(x) = 1/2√(3x² +4) * (3x² +4)' = 6x/2√(3x² +4) = 3x/√(3x² +4)
5) f(x) = x⁵ - 3 1/3 x³ +5x
f'(x) = 5x⁴-10x² +5
f'(x₀) = f'(-1) = 5 -10 +5 = 0