Given that the difference between the roots of the equation

is

.
Recall that the sum of roots of a quadratic equation is given by

.
Let the two roots of the equation be

and

, then

. . . (1)
Also recall that the product of the two roots of a quadratic equation is given by

, thus:

. . . (2)
From (1), we have:

Substituting for alpha into (2), gives:
Show more of the pic because I cant see the options for what to choose.
The range is the value of y. We know that Ix-12I is always ≥0, no matter what x is, so Ix-12I-2 is always ≥ -2, the answer is B.
Do you mean how you can tell between an area formula and a volume formula? Well usually like on a reference sheet it says the shape and the letter a or v, a representing area and v representing volume. I hope this helps, if it doesn't please tell me in the comment section