7sin^2x+3sinxcosx=5 |:cos^2x
7tg^2x+3tgx=5/cos^2x=5(tg^2x+1)
tgx=y
2y^2+3y-5=0
D=9+40=49
y1=(-3+7)/4=1; y2=(-3-7)/4=-2.5
tg(x)=1 x=pi/4+pik
tg(x)=-2.5 x=arctg(-2.5)+pik
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7sin^2x+3sinxcosx=5 |:cos^2x
7tg^2x+3tgx=5/cos^2x=5(tg^2x+1)
tgx=y
2y^2+3y-5=0
D=9+40=49
y1=(-3+7)/4=1; y2=(-3-7)/4=-2.5
tg(x)=1 x=pi/4+pik
tg(x)=-2.5 x=arctg(-2.5)+pik