Tgx+1/tgx=2
tgx≠0
tg²x-2tgx+1=0
(tgx-1)²=0
tgx=1
x=π/4+πn
π≤π/4+πn≤3π
1≤1/4+n≤3
1 -1/4≤n≤3-1/4
3/4≤n≤2 3/4
n=1 x=π/4+π=5π/4
n=2 x=π/4+2π=9π/4
4х = 18 - 7y
4x = 6 - 5y
18 - 7y = 6 - 5y
7y - 5y = 18 - 6
2y = 12
y = 6
4x = 6 - 5•6
4x = 6 - 30
X = - 24 : 4
X = - 6
Ответ ( - 6 ; 6 )
x^2+1=2x+9x^4-6x^3-11x^2+4x+4
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