1)(0,5-2х)(2х+0,5)+(0,7+х)^2=0,92-0,1х
0.25-4x^2+0.49+1.4x+x^2-0.92+0.1x=0 |*100
25-400x^2+49+140x+100x^2-92+10x=0
-300x+150x-18=0 |3
-100x+50x-6=0
D=2500-2400=100
x1=-50+10/-200=40/200=20/100=0.2
x2=-50-10/-200=60/200=0.3
2)х^2-х+3/4=0 |*4
4x^2-4x+3=0
D=16-48=-32 корней нет
3)-0,04+х^2=0
x^2=0.04
x1=0.2
x2=-0.2
5)х^2+3,2х-9=0 |*10
10x^2+32x-90=0
D=1024+3600=4624 68
x1=-32+68/20=1.8
x2=-32-68/20=-5
4)1/6х^2-х+3/4=0 |*12
2x^2-12x+9=0
D=144-72=72
x1=12+sqrt72/4=12+6sqrt2/4=6(2+sqrt2)/4=6+3sqrt2/4
x2=12-sqrt72/4=6-3sqrt2/4
sqrt - квадратный корень