Д= 441-4•5•18=441-360=81
х=-21+9/10=-1,2
х=-21-9/10=-3
Ответ:-1,2 и -3
<span>(√13-√6)(√13+√6) = 7</span>
1)tgx=0⇒x=πn
2)sin2x=-1/2⇒2x=(-1)^n+1 *π/6+πn⇒x=(-1)^n+1 *π/12+πn/2
3)tgx/4=1⇒x/4=π/4+πn⇒x=π+4πn
4)9cosx=sinx
9cos²x/2-9sin²x/2-2sin²/2cosx/2=0 /cos²x/2≠0
9tg²x/2+2tgx/2-9=0
tgx/2=a
9a²+2a-9=0
D=4+324=328 √D=2√82
a1=(-2-2√82)/18=-(1+√82)/9⇒tgx/2=-(1+√82)/9⇒x=-2arctg(1+√82)/9+πn
a2=(-2+2√82)/18=(-1+√82)/9⇒tgx/2=(-1+√82)/9⇒x=2arctg(-1+√82)/9+πn
[x²(x-3)-(x-3)]/[(x+1)(x+2)]>0
(x-3)(x²-1)/(x+1)(x+2)]>0
(x-3)(x-1)(x+1)/[(x+1)(x+2)]>0
(x-3)(x-1)/(x+2)>0,x≠-1
x=3 x=1 x=-2
_ + + _ +
--------(2) ---------(-1)-----------(1)----------(3)-----------
x∈(-2;-1) U (-1;1) U (3;∞)