D=3²-4·(-18)=9+72=81
x=(-3-9)/2=-6 или х=(-3+9)/2=3
О т в е т. -6; 3
(1/5а + 1/7а)·а²/4 = 12/35а·а²/4 = 3а/35 = 3·7,7/35 = 3·1,1/5 = 3,3 /5 = 0,66
(2-x)/4-(5x-2)/10>(3-x)/5
5(2-x)/5*4-2(5x-2)/2*10>4(3-x)/4*5
(10-5x)/20-(10x-4)/20>(12-4x)/20 /*20
10-5x-10x+4>12-4x
4x-5x-10x>-10-4+12
-11x>-2
x<-2/-11
x<0.18182