How to find a solution set

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1

Given the follow inequality, which of the following presents a range of possible answers for the inequality: –3 < 3x + 2 ≤ 3.5

( –2, 2)

0

(–1,1)

0

(–1, ½)

CORRECT

(½, 1)

0

(–3, 1/2)

0

Explanation

If you plug in the outer limits of the given ranges, (–1, ½) is the only combination that fits within the given equation. It is important to remember that "<" means “less than,” and "≤" means “less than or equal.” For example, if you answered (–2,2), plugging in 2 would make the the expression equal 8, which is greater than 3.5. And plugging in –2 for x would make the expression equal –4, which is less than –3, not greater. However, plugging in the correct answer (–1, ½) gives you –1 as your lower limit and 3.5 as your upper limit, which satisfies the equation. Both limits of the data set must satisfy the equation.

2

When you multiply a number by 5 and then subtract 23, the result is the same as when you multiplied the same number by 3 then added 3. What is the number?

5

0

6

0

7

0

10

0

13

CORRECT

Explanation

You set up the equation 5x – 23 = 3x + 3, then solve for x, giving you 13.

3

What is the product of the two values of that satisfy the following equation?

\small x^2+5x+4=0

CORRECT

0

0

0

Explanation

First, solve for the values of x by factoring.

\small x^2+5x+4=(x+1)(x+4)=0

\small (x+1)=0 or \small (x+4)=0

Then, multiply the solutions to obtain the product.

\small (-1)(-4)=4

4

When you divide a number by 3 and then add 2, the result is the same as when you multiply the same number by 2 then subtract 23. What is the number?

2

0

3

0

15

CORRECT

7

0

9

0

Explanation

You set up the equation and you get: (x/3) + 2 = 2_x –_ 23.

Add 23 to both sides: (x/3) + 25 = 2_x_

Multiply both sides by 3: x + 75 = 6_x_

Subtract x from both sides: 75 = 5_x_

Divide by 5 and get x = 15

5

|2x – 25| – 3 = 7. There are two solutions to this problem. What is the sum of those solutions?

25

CORRECT

7.5

0

10

0

17

0

Explanation

First, simplify the equation so the absolute value is all that remains on the left side of the equation:

|2_x_ – 25| = 10

Now create two equalities, one for 10 and one for –10.

2_x_ – 25 = 10 and 2_x_ – 25 = –10

2_x_ = 35 and 2_x_ = 15

x = 17.5 and x = 7.5

The two solutions are 7.5 and 17.5. 17.5 + 7.5 = 25

6

Solve for y: y+2=2y-7 +.25(y-3)

7.8

CORRECT

6.5

0

2.3

0

12.1

0

8.1

0

Explanation

Collecting terms leaves -1.25y=-9.75

And dividing by -1.25 yields 7.8

7

If , what is the product of the largest and smallest integers that satisfy the inequality?

–10

0

–5

0

0

CORRECT

5

0

7

0

Explanation

The inequality in the question possesses an absolute value; therefore, we most solve for the variable being less than positive 6 and greater than negative 6. Let's start with the positive solution.

Add 4 to both sides of the inequality.

Divide both sides of the inequality by 2.

Now, let's solve for the negative solution

Add 4 to both sides of the inequality.

Divide both sides of the inequality by 2.

Using these solutions we can write the following statement:

The smallest integer that satisfies this equation is 0, and the largest is 4. Their product is 0.

8

|10 2| – |1 – 9| = ?

0

CORRECT

16

0

2

0

8

0

Explanation

When taking the absolute value we realize that both absolute value operations yield 8, which gives us a difference of 0.

9

Find the sum of the solutions to the equation:

2x2 2x 2 = 1 x

0

0

0

CORRECT

0

Explanation

First, we need to get everything on one side so that the equation equals zero.

2x2 - 2x -2 = 1-x

We need to add x to the left, and then subtract 1.

2x2 - 2x -2 +x - 1 = 0

2x2 - x - 3 = 0

Now we need to factor the binomial. In order to do this, we need to multiply the outer two coefficients, which will give us 2(-3) = -6. We need to find two numbers that will mutiply to give us -6. We also need these two numers to equal -1 when we add them, because -1 is the coefficient of the x term.

If we use +2 and -3, then these two numbers will multiply to give us -6 and add to give us -1. Now we can rewrite the equation as follows:

2x2 - x - 3 = 2x2 + 2x - 3x - 3 = 0

2x2 + 2x - 3x - 3 = 0

Now we can group the first two terms and the last two terms. We can then factor the first two terms and the last two terms.

2x(x+1) -3(x+1) = 0

(2x-3)(x+1) = 0

This means that either 2x - 3 = 0, or x + 1 = 0. So the values of x that solve the equation are 3/2 and -1.

The question asks us for the sum of the solutions, so we must add 3/2 and -1, which would give us 1/2.

10

If 3y = 2x – 7, then which of the following statements is correct?

x is greater

0

y is greater

0

they are equal

0

not enough information given

CORRECT

Explanation

If we set one variable to the other we would get y = (2x – 7)/3 or x = (3y + 7)/2, but we aren't given any clues to what the values of x and y are and we can assume they could be any number. If x = 7/2, then y = 0. If y = -7/3, then x = 0. Let's try some other numbers. If y = –10, then x = –37/2. So for the first two examples, x is greater than y. In the last example, y is greater than x. We need more information to determine whether x or y is greater. The correct answer is not enough information given.