4x**2-2x-0.75=0
D=4+4(4*0.75)=4+12=16
x1=(2+4)/8=3/4=0.75
x2=(2-4)/8=-1/4=-0.25
4x^2 - 2x - 3/4 = 0
16x^2 - 8x -3 = 0
D = 64 + 192 = 256
x₁=(8+16)/(2*16) = 3/4
x₂=(8-16)/(2*16) = -1/4