а) (х+4)(х+5)-5≤7 б) 6-(2х+1,5)(4-х)≥0 в)(3х+2)(х-1)+(2х+1)(2х-1)<6х2-х+1 г)(2,5-3х)2-8х2 ≥2,75-15х
а) (х+4)(х+5)-5≤7 x+4x+5-5<=7 5x<=-5+5+7 5x<=7 x<=7/5=1,4 б) 6-(2х+1,5)(4-х)≥0 6-2x-6-x>=0 -3x>=-6+6 x>=-3 в)(3х+2)(х-1)+(2х+1)(2х-1)<6х2-х+1 3x+2x-1+2x+2x-1<6x^2-x+1 -6x^2+3x+2x+2x+2x+x<1+1+1 -6x^2+10x-3<0 |*(-1) 6x^2-10x+3=0 D=(-10)^2-4*6*3=100-72=28 x1=-10+28/12=1,5 x2=-10-28/12=3,16 г) (2,5-3х)2-8х2 ≥2,75-15х 5-6x-8x^2>=2,75-15x -8x^2-6x+15x>=-5+2,75 -8x^2+9x+2,25>=0 |*(-1) 8x^2-9x-2,25 D=(-9)^2-4*8*(-2,25)=81+72=153 x1=9+153/16=10,125 x2=9-153/16=-9
