First pull out 3u from both terms.

3u⁴ – 24uv³ = 3u(u³ – 8v³) = 3u[u³ – (2v)³]

This is a difference of cubes. You will see this type of factoring if you get to the challenging questions on the GRE. They can be a pain to remember but pat yourself on the back for getting to such hard questions! The difference of cubes formula to remember is a³ – b³ = (a – b)(a² + ab + b²). In our problem, a = u and b = 2v, so 

3u⁴ – 24uv³ = 3u(u³ – 8v³) = 3u[u³ – (2v)³]

                = 3u(u – 2v)(u² + 2uv + 4v²)

To begin, let's factor the first two terms and the second two terms separately.  

z³ – z² – 9z + 9 = (z³ – z²) + (–9z + 9) = z²(z – 1) – 9(z – 1)

(z – 1) can be pulled out because it appears in both terms. 

z³ – z² – 9z + 9 = (z³ – z²) + (–9z + 9) = z²(z – 1) –  9(z – 1) = (z – 1)(z² – 9)

(z² – 9) is a difference of squares, so we can use the formula a² – b² = (a – b)(a + b).

z³ – z² – 9z + 9 = (z³ – z²) + (–9z + 9) = z²(z – 1) – 9(z – 1)

                     = (z – 1)(z² – 9)

                     = (z – 1)(z – 3)(z + 3)

We know the equation a² – b² = (a + b)(a – b) for the difference of squares. Since y² is the square of y, and 4 is the square of 2, the correct answer is  (y + 2)(y – 2).

Factor the equation by finding two numbers that add to -3 and multiply to -28.

Factors of 28: 1,2,4,7,14,28

-7 and 4 work.

(x-7)(x+4) = 0

Set each equal to zero:

x=7,-4

Since  is positive, we can divide both sides of the inequality by :

 or .

For the second equation, solve for  in terms of .

Plug this value of y into the first equation.

Don't forget to switch the inequality direction if you multiply or divide by a negative.

Now that we have the equation in slope-intercept form, we can see that the y-intercept is 6.

Begin by adding  to both sides, this will get the variable isolated:

Or...

Next, divide both sides by :

Notice that when you divide by a negative number, you need to flip the inequality sign!

Choice a is equivalent because we can say that technically we are multiplying two fractions together: (xy)/z and (5(x + y))/1.  We multiply the numerators together and the denominators together and end up with xy (5x + 5y)/z.  xy (5y + 5x)/z is also equivalent because it is only simplifying what is inside the parentheses and switching the order- the commutative property tells us this is still the same expression.  5x²y + 5xy²/z is equivalent as it is just a simplified version when the numerators are multiplied out.  Choice 5x² + y²/z is not equivalent because it does not account for all the variables that were in the given expression and it does not use FOIL correctly.

First, we need to find all of the values that are in the set S, and then we need to find the values in T. Once we do this, we must find the numbers in the intersection of S and T, which means we must find the values contained in BOTH sets S and T.

S contains all of the values of x such that 2x + 4 < 8. We need to solve this inequality.

2x + 4 < 8

Subtract 4 from both sides.

2x < 4

Divide by 2.

x < 2

Thus, S contains all of the values of x that are less than (but not equal to) 2. 

Now, we need to do the same thing to find the values contained in T.

-2x + 3 < 8

Subtract 3 from both sides.

-2x < 5

Divide both sides by -2. Remember, when multiplying or dividing an inequality by a negative number, we must switch the sign.

x > -5/2

Therefore, T contains all of the values of x that are greater than -5/2, or -2.5.

Next, we must find the values that are contained in both S and T. In order to be in both sets, these numbers must be less than 2, but also greater than -2.5. Thus, the intersection of S and T consists of all numbers between -2.5 and 2.

The question asks us to find the sum of the integers in the intersection of S and T. This means we must find all of the integers between -2.5 and 2.

The integers between -2.5 and 2 are the following: -2, -1, 0, and 1. We cannot include 2, because the values in S are LESS than but not equal to 2. 

Lastly, we add up the values -2, -1, 0, and 1. The sum of these is -2.

The answer is -2.