Решение смотри в приложении
A) a^2 -2a -a^2>5-3a
-2a>5-3a
3a-2a>5
a>5
б) 9x^2 -3x -9x^2 <3x+6
-3x<3x+6
-3x-3x<6
-6x<6
x>1
В) 5y^2 -5y^2 -20y>=100
-20y>=100
y<=-5
г) 7c^2 -14c -7c^2 -c<3
-14c-c<3
-15c<3
c>-1/5
Tg(b + pi/3) = 2√3
tg(b + pi/3) = (tgb + tg(pi/3))/(1 - tgb*tg(pi/3)) = (tgb + √3) / (1 - √3*tgb) = 2√3
ctgb = 1/tgb
(tgb + √3) / (1 - √3*tgb) = 2√3
2√3*(1 - √3*tgb) = tgb + √3
2√3 - 6tgb = tgb + √3
7tgb = √3
tgb = √3/7
ctgb = 7/√3
<span>1) -5x=7-3(3+2x)
</span><span> -5x=7-9-6x
</span> -5x+6х=-2
х=-2
<span>2) 8x+3=1-(2x+4)
</span><span> 8x+3=1-2x-4
8х+2х=-3-3
10х=-6
х=-0,6</span>