(7cosa - 4(2cos²a-1))/(4cos²a-(2cos²a-1))=(-cos²a+4)/(2cos²a+1)
<span>5х-9(2+х)<-8х-6
5x-18-9x<-8x-6
4x<12
x<3 x∈(-∞;3)
9х-5(-7+4х)<-9х+10
9x+35-20x<-9x+10
2x>25
x>12.5 x∈(12.5;+∞)</span>
(x-6)(3+x)<=0
__________[-3]_________[6]__________
+ - +
x e [-3; 6]
5х/2 +0,2х=0
5х+0,4х=0
5.4х=0
х=0:5,4
х=0