1. 1x^2 -5x +4 =0
D = b^2 - 4ac = (-5)^2 - 4*1*4 = 9
x1 = 5 + 3 /2 = 8/2 =4
x2 = 5 -3 /2 = 2/2 = 1
2. x^2 -3x-10 =0
D = (-3)^2 + 4*1*(-10) = 49
x1=3+7 / 2 = 10/2 = 5
x2=3-7 /2 = -4/2=-2
3. 2x^2+ 3x-5=0
D= (2)^2 + 4*3*(-5) = 64
x1=-3+8 /4 = -4/4 = -1
x2=-3-8 /4 =-11/4 = -2,75
4. 5x^2-7x-6=0
D=(2)^2 + 4*5*(-6) = 169
x1=-7+13 /10=6/10=0,6
x2=-7-13 /10=-20/10=-2