tgx-2tgx/(1-tg^2x)=(tg^3x-tgx)/(1-tg^2x)=tgx(tg^2x-1)/(1-tg^2x)=-tgx
<span> х(4х + 5) - 7(4х +5) = 0
(х - 7)(4х + 5) = 0
х - 7 = 0 или 4х + 5 = 0
х = 7 4х = -5
х = -1,25
Ответ: х=-1,25; х = 7</span>
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