How to find a solution set - SAT Math

Card 0 of 20

Question

Using the ordered pairs listed below, which of the following equations is true?

(0, –4)

(2, 0)

(4, 12)

(8, 60)

Answer

You can solve this problem using the guess and check method by substituting the first number in the ordered pair for "x" and the second number for "y". Therfore the correct answer is y=x^{2}-4

–4 = 0 – 4

0 = 4 – 4

12 = 16 – 4

60 = 64 – 4

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Question

Let be an integer that can be represented by . If , , and are integers such that , and , what is a possible value for ?

Answer

In order to find n, we need to figure out possible values for a, b, and c.

We are told that a, b, and c are integers. We are also told that 0 < a < b < c, which means that a, b, and c are all positive. It also means that a, b, and c are different numbers (they cannot be equal). It also means that a is the smallest, and c is the largest.

We are now told that a + b + c = 7.

Let's start with the smallest possible value that a could be. The smallest integer greater than 0 is 1.

Let us assume that a = 1.

If a = 1, then b > 1. The smallest integer that b can be is 2. So let's assume b = 2.

If a =1 and b = 2, then 1 + 2 + c = 7. This means that c = 4.

If a =1, b = 2, and c = 4, then all of the conditions for a, b, and c are met. Thus, we can use these values to find n.

What if we had assumed that a was 2? If a is 2, then the smallest value that b could be is 3. If a + b + c = 7, then c would have to be 2. But we are told that c is the largest number, so it can't be equal to 2.

Thus, the only value of a that works is 1.

Let's assume that if a = 1, then b = 3. If a + b + c = 7, then c = 3. However, we are told that c > b. Thus, b cannot be 3.

Thus, b must equal 2, and c must equal 4, and a must be 1. This is the only possibility that satisfies all of the criteria given in the question.

Now we can use the values of a, b, and c to find n.

n =2a3b5c

n = 213254 = 2(9)(625) = 11250.

The answer is 11250.

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Question

Find the sum of all of the integer values of x that satisfy the following inequality:

|4 – 2x| < 5

Answer

In general, when we take the absolute value of a quantity, we can represent it as either itself, or as its additive inverse.

In other words, |x| = x (if x > 0) or |x| = –x (if x < 0).

Therefore, we can represent |4 – 2x| as either 4 – 2x or as –(4 – 2x). We must consider both of these cases and solve for x. Let’s us first consider the case that |4 – 2x| = 4 – 2x.

4 – 2x < 5

We can add 2x to both sides

4 < 2x + 5

Then subtract 5 from both sides.

–1 < 2x

Divide by 2.

–1/2 < x

x > –0.5

Now, we consider the case that |4 – 2x | = –(4 – 2x).

–(4 – 2x) < 5

Multiply both sides by negative one. Remember, whenever we multiply or divide an inequality by a negative number, we must flip the inequality sign.

4 – 2x > –5

Add 2x to both sides.

4 > 2x – 5

Add 5 to both sides.

9 > 2x

Divide by 2,

9/2 > x

4.5 > x

This means that the values of x that satisfy the original quality must be greater than -0.5 AND less than 4.5.

The question asks us to find the sum of the integer values of x that satisfy the inequality. The only integers between -0.5 and 4.5 are the following: 0, 1, 2, 3, and 4.

The sum of 0, 1, 2, 3, and 4 is 10.

The answer is 10.

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Question

How many distinct solutions does the following polynomial have?

x(x_2 – 14_x + 49) = 0

Answer

There are 3 solutions: 0, 7, 7.

The correct answer is 2 distinct solutions, however, because 7 occurs twice. So the two distinct solutions are 0 and 7.

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Question

Find the product of the values of that satisfy the following equation:

Answer

Because we are dealing with an absolute value on the left side, we are going to have to consider two possible cases. Remember that, in general, |a| = a if a > 0, and |a| = –a if a < 0. In other words, we need to consider two cases for the left side: x_2 – 2_x – 8 and –(x_2 – 2_x – 8).

Case 1: |x_2 – 2_x – 8| = x_2 – 2_x – 8 = 2_x_ + 4

x_2 – 2_x – 8 = 2_x_ + 4

Subtract 2_x_ from both sides.

x_2 – 4_x – 8 = 4

Subtract 4 from both sides.

x_2 – 4_x – 12 = 0

We must think of two numbers that multiply to give us –12 and add to give –4. These two numbers are –6 and 2. This means we can factor the left side as follows:

x_2 – 4_x – 12 = (x – 6)(x + 2) = 0

Set each of the factors equal to 0.

x – 6 = 0

Add 6 to both sides.

x = 6

Next, x + 2 = 0

Subtract 2 from both sides.

x = –2

The values of x that solve the equation are –2 and 6.

However, before moving on to the next case, it's always important to check our work. Let's put x = –2 and x = 6 into our original equation and make sure that both sides are the same.

|x_2 – 2_x – 8| = 2_x_ + 4

Let x = –2:

|x_2 – 2_x – 8| = |(–2)2 – 2(–2) – 8| = |4 + 4 – 8| = 0

2_x_ + 4 = 2(–2) + 4 = 0

x = –2 is a solution.

Let x = 6:

|62 – 2(6) – 8| = |36 – 12 – 8| = 16

2_x_ + 4 = 2(6) + 4 = 16

x = 6 is also a solution.

Case 2: |x_2 – 2_x – 8| = –(x_2 – 2_x – 8) = 2_x_ + 4.

–(x_2 – 2_x – 8) = 2_x_ + 4

Distribute the –1.

–x_2 + 2_x + 8 = 2_x_ + 4

Subtract 2_x_ from both sides.

_–x_2 + 8 = 4

Subtract 8 from both sides.

_–x_2 = –4

Divide both sides by negative 1.

_x_2 = 4

Take the square root.

x = 2 or –2

We have already established that x = –2 is a solution. Let's check to see if 2 is also a solution by going back to the original equation |x_2 – 2_x – 8| = 2_x_ + 4.

|x_2 – 2_x – 8| = |22 – 2(2) – 8| = |–8| = 8

2_x_ + 4 = 2(2) + 4 = 8

This means x = 2 is also a solution.

To summarize, the solutions to x are –2, 2, and 6.

We are asked to find their product, which is –2(2)(6) = –24.

The answer is therefore –24.

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Question

Solve _x_2 – 48 = 0.

Answer

No common terms cancel out, and this isn't a difference of squares.

Let's move the 48 to the other side: _x_2 = 48

Now take the square root of both sides: x = √48 or x = –√48. Don't forget the second (negative) solution!

Now √48 = √(3*16) = √(3*42) = 4√3, so the answer is x = 4√3 or x = –4√3.

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Question

What is the sum of all solutions to the equation

\dpi{100} \small |x+3| = 10 ?

Answer

If \dpi{100} \small |x+3| = 10, then either

\dpi{100} \small x+3 = 10 or \dpi{100} \small x+3 = -10.

These two equations yield \dpi{100} \small 7 and \dpi{100} \small -13 as answers.

\dpi{100} \small 7+(-13)=-6

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Question

Solve for x: (x-8)^{2}=36

Answer

First, take the square root of both sides:

x-8=\pm 6

Therefore, x-8=6 or x-8 = -6

Add 8 to both sides of the equation; therefore, x=14 or x=2

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Question

What is a possible solution to this equation: y= x^{2}+3x-2?

Answer

This equation can be solved using the guess and check method.

3^{2}+(3\times 3)-2= 9+9-2=16

Therefore, the ordered pair (3, 16) is the correct answer.

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Question

0.1(x-5)+0.03(2x+5)=0.5(x)

Answer

First multiply each decimal number in each term by 100 to remove the decimals (to get a whole number you have to multiply 0.03 by 100 to get 3). You need to do this for terms on both sides of the equal sign.

The second method would be to look for the number of digits to the right of the decimal point (e.g., 0.03 has two digits). So in this method shift the decimal point to the right two places.

Now the equation looks as follows:

10x-50+6x+15=50x

Now solve for x and x will be equal to -\frac{35}{34}.

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Question

Solve |z-2|\leq 0

Answer

Absolute value is the distance from the point to the origin, so the value itself is always poisitive. The only solution that makes sense for this problem is when the absolute value is equal to zero, or z-2=0 and that happens when z=2.

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Question

In this question we describe the solution set in the form of a line diagram. Remember a solution to an inequality can be described in the form of (1) Inequality notation, (2) A line diagram, (3) and or an interval notation.

Given a solution set for a linear inequality as shown below:

\left { x|x<-2 \ or\ x>3 \right }

what would be the correct representation of the above set in the form of a line diagram

Answer

The solution lies in the set of real numbers less than -2 or the set of real numbers greater than 3.

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Question

Give the solution set of the inequality

Answer

In an absolute value inequality, the absolute value expression must be isolated on one side first. We can di this by first subtracting 42 from both sides:

Divide by , reversing the direction of the inequality symbol since we are dividing by a negative number:

This inequality can be rewritten as the compound inequality

or

Solve each simple inequality separately.

Subtract 19 from both sides:

Divide by , remembering to reverse the symbol:

In interval notation, this is .

Carry out the same steps on the other simple inequality:

In interval notation, this is .

Since the two simple inequalities are connected by an "or", their individual solution sets are connected by a union; the solution set is

.

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Question

Solve and describe your answer in both inequality notation and interval notation:

10< -3a+10\leq 34

Answer

This is a question with double inequality.

First solve the left side which will be 10< -3a+10 which will give you a<0 and then solve the right side which is -3a+10\leq 34 and solution is -a\leq 8 which is really equal to a\geq -8

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Question

\left | 2x-3 \right |\leq 5

Answer

This question deals with absolute value inequalities and as a result you get a set of solutions.

The first solution involves solving 2x - 3\leq 5 which gives you x\leq 4.

Next solve for 2x-3\geq -5 which will give you x\geq -1.

Since x\leq 4 and x\geq -1 overlap, the correct solution is \[-1,4\]

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Question

.63475634... : What is the 22nd digit after the decimal?

Answer

The repeating pattern after the decimal is 63475, so the 22nd number would be 3.

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Question

\left | x+3 \right |\leq -4

Answer

This problem deals with absolute value inequalities.

An absolute value expression can never be less than 0. So the correct answer is "No Solution"

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Question

In the two equations below, and . What is the value of ?

Answer

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Question

The set contains all multiples of . Which of the following sets are contained within ?

I. The set of all multiples of .

II. The set of all multiples of .

III. The set of all multiples of .

Answer

Think of the multiples of 10: 10, 20, 30, 40, 50, 60, 70, . . .

I. Multiples of 2: 2, 4, 6, 8, 10, 12, 14, . . .

Some of these already are not contained in S.

II. Multiples of 5: 5, 10, 15, 20, 25, . . .

Some of these already are not contained in S.

III. Multiples of 20: 20, 40, 60, 80, 100, . . .

All of these are also multiples of 10. Thus, our answer must be III only.

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Question

Different colored marbles are placed in a bag. There are red marbles, black marbles, and green marbles in the bag. What is the probability that a green marble will be chosen?

Answer

When doing probability problems, we are looking for the number of successes over number of possible outcomes. There are 4 chances to successfully choose a green marble. The number of possible outcomes are 11, one for each of the 11 marbles in the bag. When we write the fraction, we get our answer.

In mathematical words we get the following:

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