<span>3х² + 6 = х² + 5х + 6
2x</span>² - 5x = 0
x(2x - 5) = 0
x = 0 или 2x - 5 = 0
x = 0 или 2x = 5
x = 0 или x = 5/2 = 2,5
Ответ: 0 ; 2,5
1)ax+15=24-4a
ax=9-4a
x=(9-4a)/a
2)5-ax=8a-8
ax=13-8a
x=(13-8a)/a
Sin 120 = Sin (90+30) = Sin (pi/2 + 30) = cos 30 = (корень из 3)/2
Cos 75 = cos (45+30) = cos 45 * cos 30 - sin 45 * sin 30 = <span>√3/2*√2/2 - 1/2*√2/2 = √6/4 - √2/4=(√6-√2)/4</span>