Which of the following equations have complex roots?

A. x^2=-7x-2

B. x^2+3x+9=0

C. x^2=5x-1

D. x^2=-7x+2

B

Step-by-step explanation:

A:

Completing the square: (x + 7/2) ^2 = - 2 + 49/4 = 41/4, in the next step you'll be square rooting a positive number so it'll have real roots.

B:

Completing the square: (x+3/2) ^2 = - 9 + 9/4 = - 27/4, you'll next be square rooting a negative number, so it'll have complex roots

C:

Completing the square: (x-5/2) ^2 = - 1 + 25/4 = 21/4, next you'll square root a positive number, so real roots

D:

Completing the square: (x+7/2) ^2 = 2 + 49/4 = 57/4, square root a positive number, so real roots.