N=22
17 - простое число, 357:17=21
21+1 = 22
<span><span>ctg^2a-tg^2a=cos^2a/sin^2a-sin^2a/cos^2a=(cos^4a-sin^4a)/cos^2a*sin^2a=cos2a/(sinacosa)^2
(cos^2a-sin^2a)/(cos2a)/(sinacosa)^2=sin^2a*cos^2a</span></span>
(2a + 5b)(5b - 2a) + (-2a - 5b).
10ab - 4a² + 25b² - 10ab - 2a - 5b.
-4a² + 25b² - 2a - 5b.
2a - 5b.
X^4-x^3-x+1=x^3(x-1)-(x-1)=(x^3-1)(x-1)=(x-1)(x^2+x+1)(x-1)=(x-1)^(2)(x^2+x+1)