<span> наверно имеется в виду: y=x^2-4x+5</span>
(a-6)²+2a(3-2a)=a²-24a+36+6a-4a²=-3a²-18a+36 вот так
<span>Sin3x+Sin2x+Sinx=0
2Sin2xCosx + Sin2x = 0
Sin2x(2Cosx +1) = 0
Sin2x = 0 или 2Cosx +1 = 0
2x = </span>πn , n ∈Z Cosx = -1/2
<span>x = </span>πn/2, n ∈Z x = +-arcCos(-1/2) + 2πk , k ∈Z
x = +-2π/3 + 2πk , k ∈Z <span>
</span>
B³-b²-7b+3b²-3b-21=b³+2b²-10b-21