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| 11 Theory slides |
| 10 Exercises - Grade E - A |
| Each lesson is meant to take 1-2 classroom sessions |
Here are a few recommended readings before getting started with this lesson.
A power is the product of a repeated factor. A power expression consists of two parts. The base is the repeated factor and the exponent indicates how many times the base is used as a factor. Consider, for example, the power expression with base 7 and exponent 4.
Expression | Example 1 | Example 2 |
---|---|---|
22 | 2 to the second power |
2 squared |
73 | 7 to the third power |
7 cubed |
54 | 5 raised to the power of 4 |
5 raised to the fourth power |
squaredor
cubed,respectively. Expressions for greater powers are all usually read as the last example on the table.
Tearrik is participating on a trivia contest at school.
At the moment, he is on the bonus question round. Each question that he answers correctly doubles the amount of bonus points he gets. The first question is worth two bonus points. The table below displays the bonus points Tearrik will earn if he answers 1, 2, or 3 questions correctly.
Questions Answered Correctly | Points | Simplify |
---|---|---|
1 | 2 | 2 |
2 | 2⋅2 | 4 |
3 | 2⋅2⋅2 | 8 |
Associative Property of Multiplication
Multiply
Associative Property of Multiplication
Multiply
Multiply
Find the value of the given power.
The numbers that result from raising an integer to the power of 2 appear frequently in math. These numbers are called perfect squares.
Example | Rewrite as a Product | Perfect Square? | Explanation |
---|---|---|---|
25 | 5×5=52 | Yes ✓ | 5 is an integer. |
30.25 | 5.5×5.5=5.52 | No × | 5.5 is not an integer. |
32 | 5.656…×5.656…=(5.656…)2 | No × | 5.656… is not an integer. |
64 | 8×8=82 | Yes ✓ | 8 is an integer. |
Similar to perfect squares, there are numbers called perfect cubes.
Example | Rewrite as a Product | Perfect Cube? | Explanation |
---|---|---|---|
125 | 5×5×5=53 | Yes ✓ | 5 is an integer. |
166.375 | 5.5×5.5×5.5=5.53 | No × | 5.5 is not an integer. |
64 | 4×4×4=43 | Yes ✓ | 4 is an integer. |
270 | 6.463…×6.463…×6.463…=(6.463…)3 | No × | 6.463… is not an integer. |
One of the questions that Tearrik could not answer in the trivia contest was about perfect squares. Now he wants to study harder so that he does not make the same mistake twice!
Determined to improve, he decides to also study perfect cubes. Help Tearrik solve the following exercises.
It can be noted that 27 is not a perfect square. Now, to determine if 136 is a perfect square, remember that the square of 10 is 100. The consecutive perfect squares are displayed in the table below.
Number | Square | Less Than, Greater Than, or Equal to 136? |
---|---|---|
10 | 102=100 | 100<136 |
11 | 112=121 | 121<136 |
12 | 122=144 | 144>136 |
As shown in the table, 136 is greater than 121 but less than 144. Since 136 lies between two consecutive perfect squares, 136 cannot be a perfect square. More perfect squares will be identified to determine if 225 is a perfect square.
Number | Square | Less Than, Greater Than, or Equal to 225? |
---|---|---|
13 | 132=169 | 169<225 |
14 | 142=196 | 196<225 |
15 | 152=225 | 225=225 |
The number 225 is the square of 15. Since 15 is an integer, 225 is a perfect square. The remaining number is 729. The square of 20 is 400. The square of 30 is 900. Since 729 is closer to 900 than to 400, it might be convenient to start with 30 and explore the next perfect squares in decreasing order.
Number | Square | Less Than, Greater Than, or Equal to 729? |
---|---|---|
30 | 302=900 | 900>729 |
29 | 292=841 | 841>729 |
28 | 282=784 | 784>729 |
27 | 272=729 | 729=729 |
Notice that 729 is a perfect square. Now that all numbers have been examined, the results can be summarized in another table.
Number | Perfect Square? |
---|---|
64 | Yes |
27 | No |
136 | No |
225 | Yes |
729 | Yes |
Number | Cube | Less Than, Greater Than, or Equal to 27? |
---|---|---|
2 | 23=8 | 8<27 |
3 | 33=27 | 27=27 |
Because 27 can be expressed as the cube of the number 3, it is a perfect cube. Using a similar reasoning, the number 64 will be examined.
Number | Cube | Less Than, Greater Than, or Equal to 64? |
---|---|---|
4 | 43=64 | 64=64 |
As shown, 64 is a perfect cube. Now continue the table to see if 136 is a perfect cube.
Number | Cube | Less Than, Greater Than, or Equal to 136? |
---|---|---|
5 | 53=125 | 125<136 |
6 | 63=216 | 216>136 |
The number 136 lies between two consecutive perfect cubes, so 136 is not a perfect cube. Now the number 225 will be tested. It is a good thing that 216 is really close to 225!
Number | Cube | Less Than, Greater Than, or Equal to 225? |
---|---|---|
6 | 63=216 | 136<216 |
7 | 73=343 | 343>216 |
The number 225 lies between the perfect cubes 216 and 343, meaning that 225 is not a perfect cube. Finally, 729 will be tested.
Number | Cube | Less Than, Greater Than, or Equal to 729? |
---|---|---|
8 | 83=512 | 512<729 |
9 | 93=729 | 729=729 |
Every number was examined. The results are summarized in the table below.
Number | Perfect Cube? |
---|---|
64 | Yes |
27 | Yes |
136 | No |
225 | No |
729 | Yes |
Notice that a number can be both a perfect cube and a perfect square!
Determine whether the given number is a perfect square, a perfect cube, both, or neither.
Exponent | Result |
---|---|
Even | Always positive |
Odd | Sign depends on the base |
Select the power that represents the given product.
Looking at the product, we can see that 7 is being multiplied five times. 7* 7* 7* 7* 7_5 We need to determine which number is the base and which is the exponent to write the power expression. The base is the number being multiplied and the exponent is the number of times that the base is multiplied. Let's identify which is which! Base: & 7 Exponent: & 5 Now that we know which number is the base and which is the exponent, we can write the power that corresponds to this product of repeated factors. 7* 7* 7* 7* 7_5 ⇕ 7^5
Looking at the product, we can see that this time 11 is being multiplied seven times.
11* 11* 11 * 11 * 11 * 11 * 11_7
Similar to what we did before, we will identify the base and the exponent. Now that we know how to do it, let's write them!
Base: & 11
Exponent: & 7
Now that we know which is the base and which is the exponent, we can write the power for this product.
11* 11* 11 * 11 * 11 * 11 * 11_7
⇕
11^7
Determine the value for each of the following powers.
We want to find the value corresponding to the given power. The first step that we should do is to look at the given expression. 7^4 In this expression, the number 7 is being multiplied by itself 4 times. Knowing this, we can write the power expression as a product of repeated factors. Then we can solve the multiplication expression. Let's do it!
Therefore, the expression 7^4 is equal to 2401.
Let's take another look at the given power expression.
13^2
We can answer this similarly to the way we did in Part A. First, we identify that 13 is being multiplied by itself 2 times. We can write a product of repeated factors to solve it. Let's do it!
Therefore, the expression 13^2 is equal to 169.
A perfect square is a number that can be expressed as the square of an integer. For example, the number 64 can be written as the square of 8. 8^2 = 64 Let's test different numbers to determine which of the given numbers are perfect squares. To help us identify numbers that are not perfect squares, consider the squares of 5 and 6. 5^2 = 25 6^2 = 36 Since 5 and 6 are integers, 25 and 36 are perfect squares. Since there are no integers between 5 and 6, there are no perfect squares between 25 and 36.
We can use the squares of consecutive numbers to get consecutive perfect squares. If the number we are testing is between two consecutive perfect squares, it is not a perfect square. Let's look at the given numbers from least to greatest. 325, 961, 1158, 2809, 3249 Let's start our list of perfect squares with multiples of 10. Consider that the square of 10 is 100 and the square of 20 is 400. Since 325 is less than 400, we can look at the perfect squares below 400. Also, since 325 is closer to 400 than 100, we will focus the perfect squares of integers closer to 20 than 10.
Number | Square | Less Than, Greater Than, or Equal to 325? |
---|---|---|
20 | 20^2 = 400 | 400 > 325 |
19 | 19^2 = 361 | 361 > 325 |
18 | 18^2 = 324 | 324 < 325 |
This table shows that 325 is between two consecutive perfect squares, 324 and 361. This means that 325 is not a perfect square. Next, notice that the square of 30, 900, is close to 961. Let's find the squares of the numbers just after 30. Let's do it!
Number | Square | Less Than, Greater Than, or Equal to 961? |
---|---|---|
30 | 30^2 = 900 | 900 < 961 |
31 | 31^2 = 961 | 961 = 961 |
Since 961 is the square of 31, 961 is a perfect square! Next, let's see if 1158 is a perfect square. The square of 30 is 900 and the square of 40 is 1600. Since 1158 is a little closer to 900 than to 1600, we will look at the consecutive perfect squares after 30.
Number | Square | Less Than, Greater Than, or Equal to 1158? |
---|---|---|
30 | 30^2 = 900 | 900 < 1158 |
31 | 31^2 = 961 | 961 < 1158 |
32 | 32^2 = 1024 | 1024 < 1158 |
33 | 33^2 = 1089 | 1089 < 1158 |
34 | 34^2 = 1156 | 1156 < 1158 |
35 | 35^2 = 1225 | 1225 > 1158 |
Since 1158 lies between two consecutive perfect squares, 1158 is not a perfect square. Things are going along well. Now let's look at 2809. The square of 50 is 2500 and the square of 60 is 3600, so let's find the consecutive perfect squares greater than 2500.
Number | Square | Less Than, Greater Than, or Equal to 2809? |
---|---|---|
50 | 50^2 = 2500 | 2500 < 2809 |
51 | 51^2 = 2601 | 2601 < 2809 |
52 | 52^2 = 2704 | 2704 < 2809 |
53 | 53^2 = 2809 | 2809 = 2809 |
From the table, we can see that 2809 is the square of 53. Therefore, 2809 is a perfect square. Finally, let's examine 3249. It is a good thing that we already know that the square of 60 is 3600! Let's look at the squares of the integers less than 60.
Number | Square | Less Than, Greater Than, or Equal to 3249? |
---|---|---|
60 | 60^2 = 3600 | 3600 > 3249 |
59 | 59^2 = 3481 | 3481 > 3249 |
58 | 58^2 = 3364 | 3364 > 3249 |
57 | 57^2 = 3249 | 3249 = 3249 |
We found that 3249 is also a perfect square. Now we have examined all the given numbers. Good job! Let's summarize our results in a table.
Number | Perfect Square? |
---|---|
961 | Yes |
325 | No |
2809 | Yes |
1158 | No |
3249 | Yes |
A perfect cube is a number that can be expressed as the cube of an integer. For example, the number 8 can be written as the cube of 2. 2^3 = 8 Let's test different numbers to determine which of the given numbers are perfect cubes. To help us identify numbers that are not perfect cubes, consider the cubes of 2 and 3. 2^3 = & 8 3^3 = & 27 Since 2 and 3 are integers, 8 and 27 are perfect cubes. Since there are no integers between 2 and 3, there are no perfect squares between 8 and 27.
We can use the cubes of consecutive numbers to get consecutive perfect cubes. If the number we are testing lies between two consecutive perfect cubes, then it is not a perfect cube. Let's look at the given numbers from least to greatest. 343, 526, 729, 2197, 2864 Let's start our list of perfect cubes with multiples of 10, which is 1000. The first three numbers are less than 1000 while the last two are greater. Let's look at the cubes of the integers less than 10 and compare them with the numbers in the list.
Number | Cube | Less Than, Greater Than, or Equal to 729? |
---|---|---|
10 | 10^3 = 1000 | 1000 > 729 |
9 | 9^3 = 729 | 729 = 729 |
From the table, we can see that the cube of 9 is 729, so 729 is a perfect cube. Things are going great! Let's continue this process to see if 526 is a perfect cube.
Number | Cube | Less Than, Greater Than, or Equal to 526? |
---|---|---|
9 | 9^3 = 729 | 729 > 526 |
8 | 8^3 = 512 | 512 < 526 |
In this case, we can see that 512 and 729 are consecutive perfect cubes. Since 526 lies between two consecutive perfect cubes, 526 is not a perfect cube. Let's continue until we can determine if 343 is a perfect cube.
Number | Cube | Less Than, Greater Than, or Equal to 343? |
---|---|---|
8 | 8^3 = 512 | 512 > 343 |
7 | 7^3 = 343 | 343 = 343 |
As we can see, 343 is the cube of 7. This means that 343 is a perfect cube. Now let's examine the numbers that are greater than 1000. The cube of 20 is 8000, which is much greater than 2197. Let's look at the perfect cubes closer to 1000 until we find 2197.
Number | Cube | Less Than, Greater Than, or Equal to 2197? |
---|---|---|
10 | 10^3 = 1000 | 1000 < 2197 |
11 | 11^3 = 1331 | 1331 < 2197 |
12 | 12^3 = 1728 | 1728 < 2197 |
13 | 13^3 = 2197 | 2197 = 2197 |
We found that 2197 is also a perfect cube! The only number left to consider is 2864. We will continue this process to figure out if this number is a perfect cube.
Number | Cube | Less Than, Greater Than, or Equal to 2864? |
---|---|---|
13 | 13^3 = 2197 | 2197 < 2864 |
14 | 14^3 = 2744 | 2744 < 2864 |
15 | 15^3 = 3375 | 3375 > 2864 |
Finally, we can see that 2864 is not a perfect cube. We finished examining the given numbers. Good job! Let's summarize our results in a table.
Number | Perfect Cube? |
---|---|
2197 | Yes |
729 | Yes |
526 | No |
2864 | No |
343 | Yes |
The edge length of a cube is of 6 centimeters.
The volume of a cube is found by raising the edge length to the third power. This is why we are given this power expression for the volume of the cube with a side length of 6. 6^3 To find the value of this power expression, recall that a power is the product of repeated factors. The base of the power is the repeated factor. The exponent of the power indicates the number of times the base is used as a factor.
Since 6^3 is a power, we can rewrite it as the product of repeated factors. In our case, the base is 6 and the power is 3. This means that 6 will be used as a factor 3 times. Let's find the value of this power by writing the expression and then calculating the product.
Therefore, the volume of the cube is of 216 cubic centimeters.