4sin²x -5sinxcosx - 6cos²x=0|:cos²x≠0
4tg²x-5tgx-6=0 |t=tgx
4t²-5t-6=0
D=(-5)²-4*4*(-6)=25+96=121=11²
t1=(5+11)/8=2 t2=(5-11)/8=-0,75
tgx=2 tgx=-0,75
x=arctg2+πn, n∈Z x=-arctg0,75+πn, n∈Z
1)
производная f^3(2) = 27 => 3f^2(2) * f'(2) = 27 => f'(2) = 9/f^2(2)
производная 1/f(2) = -1 => -1/f^2(2) * f'(2) = -1 => f'(2) = f^2(2)
Тогда f'(2) = 9/f'(2)
(f'(2))^2 = 9
f'(2) = ±3
=(a²-2ab+b²-a²-2ab-b²)/ab=-4ab/ab=-4