Question

Which one of the following parabolas has no real roots?

a) y = $x^{2}$ + 4x + 1
b) y = $x^{2}$ + 2x + 1
c) y = $x^{2}$ + x + 1
d) y = $x^{2}$ + 3x + 1

Answer 1

Answer:

answer is C

Step-by-step explanation:

to find how many answers roots the parabola has, we have to find Discriminant:

a) D= b^2 - 4ac= 4^2 - 4*1*1= 16 - 4= 12

D>0 so this parabola has 2 roots

b) D= b^2 - 4ac= 2^2 - 4*1*1= 4-4=0

D=0 so this parabola has 1 root

c) D= b^2 - 4ac= 1^2 - 4*1*1= 1 - 4= -3

D<0 so this parabola has no real roots

d) D= b^2 - 4ac = 3^2 - 4*1*1= 9-4= 5

D>0 this parabola has 2 roots