Х+5/6 - х/5 = 1
30x+25-6x-30=0
24x-5=0
24x=5
x=5/24
![1)2tg\frac{\pi }{3}*Ctg(-\frac{\pi }{6})+Cos\pi-2Sin\frac{\pi }{4}=2\sqrt{3}*(-\sqrt{3})-1-2*\frac{\sqrt{2}}{2}= -6-1-\sqrt{2}=-(\sqrt{2}+7)](https://tex.z-dn.net/?f=1%292tg%5Cfrac%7B%5Cpi%20%7D%7B3%7D%2ACtg%28-%5Cfrac%7B%5Cpi%20%7D%7B6%7D%29%2BCos%5Cpi-2Sin%5Cfrac%7B%5Cpi%20%7D%7B4%7D%3D2%5Csqrt%7B3%7D%2A%28-%5Csqrt%7B3%7D%29-1-2%2A%5Cfrac%7B%5Csqrt%7B2%7D%7D%7B2%7D%3D%20-6-1-%5Csqrt%7B2%7D%3D-%28%5Csqrt%7B2%7D%2B7%29)
2a) Sin124⁰ > 0
Cos203⁰ < 0
tg(- 280⁰) = - tg280⁰ < 0
( + ) * ( - ) * (- ) = ( + )
Знак выражения положительный
2б) ![Sin\frac{7\pi }{10} =Sin126^{o}>0\\\\Cos\frac{13\pi}{12}=Cos195^{o}<0\\\\(+)*(-)=(-)](https://tex.z-dn.net/?f=Sin%5Cfrac%7B7%5Cpi%20%7D%7B10%7D%20%3DSin126%5E%7Bo%7D%3E0%5C%5C%5C%5CCos%5Cfrac%7B13%5Cpi%7D%7B12%7D%3DCos195%5E%7Bo%7D%3C0%5C%5C%5C%5C%28%2B%29%2A%28-%29%3D%28-%29)
Знак выражения отрицательный
<span>x-y-3x^2+3y^2
x-3x^2 - y+3y^2
x(1-3x) - y(1-3y)
<u>(x-y)(1-3x)(1-3y)</u>
</span>