1) 4x^2=-4x-1

2) 6x^2-17x+12=0

3) 3x^2-7=4x

1) 4x^2=-4x-1

4x^2+4x+1=0

D=16-4*4*1=16-16=0

D=0

x=-b/2a

x=-4/8

x=-0,5

2) 6x^2-17x+12=0

D=289-4*6*12=289-288=1

x1,2=17+-1/12

x1=4/3; x2=1,5

2) 3x^2-7=4x

3^2-4x-7=0

D=16-4*3 * (-7) = 16+84=100

x1,2=4+-10/6

x1=-1; x2=7/3