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.

answer:   35 % is the probability of a late departure or an early arrival.

step-by-step explanation:

let l represents the late departure and e represents the early departure.

then, according to the question,

p(l) = 12 %,   p(e) = 27 % and = 4 %

and, we have to find out,

but, we know that,

which is the required equation that will use to find the probability of a late departure or an early departure.

therefore,   the probability of a late departure or an early arrival =   35 %