Answer:
A.
Step-by-step explanation:
you have to find the discriminant
b²-4ac for each equation
if discriminant < 0 no real solutions because will be negative under the squareroot whhan you try to find the roots
if discriminant = 0 there is only one solution
if discriminant > 0 two real solutions
for your given problems
A. discriminant =(-2)²-4*2*15 will be negative
Answer:

Step-by-step explanation:

Apparently, you're supposed to recognize that the formula tells you the value of cos(x/2).
6.75 is the absolute value of 6.75 absolute value is distance from zero and 6.75 is 6.75 from 0 so is -6.75