![lgsin2x=lgcosx\\ \left \{ {{sin2x>0} \atop {cosx>0}} \right. \\ sin2x=cosx\\ 2sinx*cosx=cosx\\ cosx(2sinx-1)=0\\ cosx=0\\ sinx=\frac{1}{2}\\](https://tex.z-dn.net/?f=lgsin2x%3Dlgcosx%5C%5C+%5Cleft+%5C%7B+%7B%7Bsin2x%3E0%7D+%5Catop+%7Bcosx%3E0%7D%7D+%5Cright.+%5C%5C+sin2x%3Dcosx%5C%5C+2sinx%2Acosx%3Dcosx%5C%5C+cosx%282sinx-1%29%3D0%5C%5C+cosx%3D0%5C%5C+sinx%3D%5Cfrac%7B1%7D%7B2%7D%5C%5C+)
Откуда с учетом выше стоящего неравенства получаем
![x=\frac{\pi}{2}+2\pi*n\\ x=\frac{\pi}{6}+2\pi*n](https://tex.z-dn.net/?f=x%3D%5Cfrac%7B%5Cpi%7D%7B2%7D%2B2%5Cpi%2An%5C%5C%0Ax%3D%5Cfrac%7B%5Cpi%7D%7B6%7D%2B2%5Cpi%2An)
5х²-9х+4=0
Д= 81-4*5*4=81-80=1
х1= (9+1)/10=1
х2=8/10=0.8
См фото
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<span>(х^2-8х+16)/(х^2-х-12) =0
(x-4)^2 / (x-4)(x+3) =
(x-4)/(x+3)=0
x=4
x не равен -3</span>
48 - 100%
х - 25%
х=48*25/100
Х=12
Ответ 12.
И все;)