Question

Срочно, решите Ур-ие.
2tgx-5ctgx+9=0

Answer 1

tgx=t ctgx=1/t
2t-5/t+9=0 | *t
2t²+9t-5=0
D=81-4*2*(-5)=121
t1=-9+11/4=1/2
t2=-9-11/4=-20/4=-5
tgx=1/2
x=arctg1/2+пn,n€z
tgx=-5
x=-arctg5+пn,n€z