√15876 = √(2² * 3⁴ * 7² ) = 2 * 3² * 7 = 126
1)
2x^2 - 6x+16 >= 15x -3x^2
5x^2 - 21x +16>=0
5x^2 - 21x +16=0
D = 441-320=121
x1=3.2
x2=1
(-беск.;1]u[3,2;+беск)
2)
2x^2-5x+4<=7x-3x^2
5x^2-12x+4<=0
5x^2-12x+4=0
D=144-80=64
x1=2
x2=0.4
[0.4;2]
*мастер живописи*
2sinx>1
sinx>1/2
П/6+2ПК<x<5/6П+2ПК