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Math: Middle School: Grades 6, 7 and 8 Quiz - Pre-Algebra - Monomials (Questions)

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As you have most likely come to learn by now, Algebra comes with a lot of different and interesting terminologies such as monomial, polynomial, variables and coefficients. In this quiz, we are going to focus on monomials and, more specifically, how to find the least common multiple (LCM) of monomials.

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As a quick refresher, a monomial is a polynomial that has only one term. An example of a monomial would be 2x2. It is only one term or factor on its own, as well as in a problem. [Note that the “x” is a variable.]

Now let’s list two monomials: 2x2 and 5x4

The task is to now find the LCM of these two monomials. So let’s look at the coefficients (or known numbers), i.e., “2” and “5.” We then will need to multiply each of these numbers beginning by 1, then 2, then 3, etc. until we find the first common multiple number sum. This is done as follows:

2: 2, 4, 6, 8, 10 (To find the multiples it is: 2 x 1= 2; 2 x 2 = 4; 2 x 3 = 6; 2 x 4 = 8; 2 x 5 = 10)

5: 5, 10 (To find the multiples it is: 5 x 1= 5; 5 x 2 = 10)

10 is the first least common multiple (LCM) sum of “2” and “5”.

When you have variables, the variable with the highest exponent is used as the least common multiple. In our two monomials, x4 has the highest exponent. This then tells us that the LCM of 2x2 and 5x4 is 10x4.

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1. For the monomials given below, find the LCM.

3x5, 6x3
[ ] 18x5
[ ] 18x15
[ ] 24x5
[ ] 12x5
2. For the monomials given below, find the LCM.

7x3, 9x2
[ ] 63x2
[ ] 63x3
[ ] 63x6
[ ] 63x1
3. For the monomials given below, find the LCM.

5x4, 8x7
[ ] 40x7
[ ] 13x7
[ ] 13x28
[ ] 40x11
4. For the monomials given below, find the LCM.

2x9, 4x6
[ ] 8x9
[ ] 4x15
[ ] 4x9
[ ] 8x54
5. For the monomials given below, find the LCM.

6x2, 5x3
[ ] 30x6
[ ] 30x3
[ ] 30x5
[ ] 30x2
6. For the monomials given below, find the LCM.

10x8, 2x4
[ ] 20x8
[ ] 20x32
[ ] 8x8
[ ] 10x8
7. For the monomials given below, find the LCM.

13x5, 5x2
[ ] 65x5
[ ] 18x7
[ ] 65x10
[ ] 8x5
8. For the monomials given below, find the LCM.

7x7, 3x8
[ ] 21x7
[ ] 21x8
[ ] 21x15
[ ] 21x56
9. For the monomials given below, find the LCM.

4x2, 6>x2
[ ] 24x2
[ ] 12x4
[ ] 12x2
[ ] 24x4
10. For the monomials given below, find the LCM.

11x4, 9x10
[ ] 20x14
[ ] 99x40
[ ] 99x10
[ ] 99x6
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Math: Middle School: Grades 6, 7 and 8 Quiz - Pre-Algebra - Monomials (Answers)
1. For the monomials given below, find the LCM.

3x5, 6x3
[ ] 18x5
[ ] 18x15
[ ] 24x5
[x] 12x5
3: 3 x 1 = 3; 3 x 2 = 6; 3 x 3 = 9; 3 x 4 = 12
6: 6 x 1 = 6; 6 x 2 = 12
x5 has the highest exponents
LCM is 12x5
Answer (d) is the correct answer
2. For the monomials given below, find the LCM.

7x3, 9x2
[ ] 63x2
[x] 63x3
[ ] 63x6
[ ] 63x1
7: 7 x 1 = 7; 7 x 2 = 14; 7 x 3 = 21; 7 x 4 = 28; 7 x 5 = 35; 7 x 6 = 42; 7 x 7 = 49; 7 x 8 = 56; 7 x 9 = 63
9: 9 x 1 = 9; 9 x 2 = 18; 9 x 3 = 27; 9 x 4 = 36; 9 x 5 = 45; 9 x 6 = 54; 9 x 7 = 63
x3 has the highest exponents
LCM is 63x3
Answer (b) is the correct answer
3. For the monomials given below, find the LCM.

5x4, 8x7
[x] 40x7
[ ] 13x7
[ ] 13x28
[ ] 40x11
5: 5 x 1 = 5; 5 x 2 = 10; 5 x 3 = 15; 5 x 4 = 20; 5 x 5 = 25; 5 x 6 = 30; 5 x 7 = 35; 5 x 8 = 40
8: 8 x 1 = 8; 8 x 2 = 16; 8 x 3 = 24; 8 x 4 = 32; 8 x 5 = 40
x7 has the highest exponents
LCM is 40x7
Answer (a) is the correct answer
4. For the monomials given below, find the LCM.

2x9, 4x6
[ ] 8x9
[ ] 4x15
[x] 4x9
[ ] 8x54
2: 2 x 1 = 2; 2 x 2 = 4
4: 4 x 1 = 4
x9 has the highest exponents
LCM is 4x9
Answer (c) is the correct answer
5. For the monomials given below, find the LCM.

6x2, 5x3
[ ] 30x6
[x] 30x3
[ ] 30x5
[ ] 30x2
6: 6 x 1 = 6; 6 x 2 = 12; 6 x 3 = 18; 6 x 4 = 24; 6 x 5 = 30
5: 5 x 1 = 5; 5 x 2 = 10; 5 x 3 = 15; 5 x 4 = 20; 5 x 5 = 25; 5 x 6 = 30
x3 has the highest exponents
LCM is 30x3
Answer (b) is the correct answer
6. For the monomials given below, find the LCM.

10x8, 2x4
[ ] 20x8
[ ] 20x32
[ ] 8x8
[x] 10x8
10: 10 x 1 = 10
2: 2 x 1 = 2; 2 x 2 = 4; 2 x 3 = 6; 2 x 4 = 8; 2 x 5 = 10
x8 has the highest exponents
LCM is 10x8
Answer (d) is the correct answer
7. For the monomials given below, find the LCM.

13x5, 5x2
[x] 65x5
[ ] 18x7
[ ] 65x10
[ ] 8x5
13: 13 x 1 = 13; 13 x 2 = 26; 13 x 3 = 39; 13 x 4 = 52; 13 x 5 = 65
5: 5 x 1 = 5; 5 x 2 = 10; 5 x 3 = 15; 5 x 4 = 20; 5 x 5 = 25; 5 x 6 = 30; 5 x 7 = 35; 5 x 8 = 40; 5 x 9 = 45; 5 x 10 = 50; 5 x 11 = 55; 5 x 12 = 60; 5 x 13 = 65
x5 has the highest exponents
LCM is 65x5
Answer (a) is the correct answer
8. For the monomials given below, find the LCM.

7x7, 3x8
[ ] 21x7
[x] 21x8
[ ] 21x15
[ ] 21x56
7: 7 x 1 = 7; 7 x 2 = 14; 7 x 3 = 21
3: 3 x 1 = 3; 3 x 2 = 6; 3 x 3 = 9; 3 x 4 = 12; 3 x 5 = 15; 3 x 6 = 18; 3 x 7 = 21
x8 has the highest exponents
LCM is 21x8
Answer (b) is the correct answer
9. For the monomials given below, find the LCM.

4x2, 6>x2
[ ] 24x2
[ ] 12x4
[x] 12x2
[ ] 24x4
4: 4 x 1 = 4; 4 x 2 = 8; 4 x 3 = 12
6: 6 x 1 = 6; 6 x 2 = 12
Both variables have the same exponent of x2 so the LCM is 12x2
Answer (c) is the correct answer
10. For the monomials given below, find the LCM.

11x4, 9x10
[ ] 20x14
[ ] 99x40
[x] 99x10
[ ] 99x6
11: 11 x 1 = 11; 11 x 2 = 22; 11 x 3 = 33; 11 x 4 = 44; 11 x 5 = 55; 11 x 6 = 66; 11 x 7 = 77; 11 x 8 = 88; 11 x 9 = 99
9: 9 x 1 = 9; 9 x 2 = 18; 9 x 3 = 27; 9 x 4 = 36; 9 x 5 = 45; 9 x 6 = 54; 9 x 7 = 63; 9 x 8 = 72; 9 x 9 = 81; 9 x 10 = 90; 9 x 11 = 99
x10 has the highest exponents
LCM is 99x10
Answer (c) is the correct answer