Answer:
Step-by-step explanation:
Let 
Subbing in:

a = 9, b = -2, c = -7
The product of a and c is the aboslute value of -63, so a*c = 63. We need 2 factors of 63 that will add to give us -2. The factors of 63 are {1, 63}, (3, 21}, {7, 9}. It looks like the combination of -9 and +7 will work because -9 + 7 = -2. Plug in accordingly:

Group together in groups of 2:

Now factor out what's common within each set of parenthesis:

We know this combination "works" because the terms inside the parenthesis are identical. We can now factor those out and what's left goes together in another set of parenthesis:

Remember that 
so we sub back in and continue to factor. This was originally a fourth degree polynomial; that means we have 4 solutions.

The first two solutions are found withing the first set of parenthesis and the second two are found in other set of parenthesis. Factoring
gives us that x = 1 and -1. The other set is a bit more tricky. If
then
and

You cannot take the square root of a negative number without allowing for the imaginary component, i, so we do that:
±
which will simplify down to
±
Those are the 4 solutions to the quartic equation.
Sort of, say you take 99% off of something that is $100. You will end up paying $1. Then if you take another 99% off, you wil pay $0.01. Takig another 99% off will give you $0.001, but money only goes to two decimal points, so its free from a money standpoint, but there is still a cost.
Answer:
B) Find the ratio of minutes to miles, 4:1. Multiply 7.5 by 4
Step-by-step explanation:
A bicyclist rides the same number of miles every minute. The ratio table below shows the number of miles she rides during certain amounts of time.
Biking Times and Distances
Number of Minutes Number of Miles
10 2.5
16 4
? 7.5
48 12
Which statement explains how to find the number of minutes it takes to bike 7.5 miles?
B) Find the ratio of minutes to miles, 4:1. Multiply 7.5 by 4....
Answer: The correct number of balls is (b) 4.
Step-by-step explanation: Given that a single winner is to be chosen in a random draw designed for 210 participants. Also, there is an equal probability of winning for each participant.
We are using 10 balls, numbered through 0 to 9. We are to find the number of balls which needs to be picked up, regardless of order, so that each of the 210 participants can be assigned a unique set of numbers.
Let 'r' represents the number of balls to be picked up.
Since we are choosing from 10 balls, so we must have

The value of 'r' can be any one of 0, 1, 2, . . , 10.
Now,
if r = 1, then

If r = 2, then

If r = 3, then

If r = 4, then

Therefore, we need to pick 4 balls so that each participant can be assigned a unique set of numbers.
Thus, (b) is the correct option.