Given is square root of a negative real number, i.e.
When we find square root of positive real numbers, we get Real answers.
But when we find square root of negative real numbers, we get Imaginary answers. To solve them, we can split the given negative number into product of -1 and the number itself but with positive sign. e.g. -4 = -1 x 4.
For square root of -1, we use english letter 'i' called Imaginary unit i.e. 
Now we can use -0.25 = -1 x 0.25

Hence, "0.5i" is the final answer.
Answer: C
Step-by-step explanation:
Less than or more than without "or equal" means that the dot is not shaded, otherwise it is.
So the answer is C
The lines are in the same plane but never intersect
Answer:
$43.20
Step-by-step explanation:
A swimsuit that originally cost $90 before any discount is on sale for 20% off.
X = price of swimsuit
X = 90
20% off = 90 * 0.8 = 72
The swimsuit is then put on clearance for an additional 40 % off the sale price.
72 * 0.6 = 43.2
what is the final price?
$43.20