<span>49-3х=4 </span>
<span>-3х=4-49 </span>
<span>-3х=-15 </span>
<span>х=15</span>
<span>легко</span>
<span>y=x^2-4x+4 = (x-2)^2
D(y) = (-</span>∞;+<span>∞)
Функция убывает на (-</span>∞;2]
= (cos (11π/24-5π/24)- cos (11π/24+5π/24))/2=(cos π/4 - cos 2π/3)/2= (√2/2+1/2)/2=(√2+1)/4