Examples with solutions for Associative Property: Using variables

Exercise #1

Solve the following problem:

11x×5×6= 11x\times5\times6=

Video Solution

Step-by-Step Solution

Upon observing the exercise note that we have two "regular" numbers and one number with a variable.
Given that this is a multiplication exercise, multiplying a number with a variable by a number without a variable doesn't present a problem.

In fact, it's important to remember that a variable attached to a number represents multiplication itself, for example in this case: 11×x 11\times x
Therefore, we can apply the distributive property to separate the variable, and come back to it later.
Proceed to solve the exercise from right to left since it's simpler this way.

5×6=30 5\times6=30

We obtain the following:

11x×30= 11x\times30=

We'll put aside the x and add it at the end of the exercise.

By solving the exercise in an organized way we simplify the solution process.

It's important to maintain the correct order when solving the problem, meaning first multiply the ones of the first number by the ones of the second number,
then the tens of the first number by the ones of the second number, and so on.

30×11=330 30\\\times11\\=330

Don't forget to add the variable at the end. The answer is as follows:

330x 330x

Answer

330x 330x

Exercise #2

Solve the following problem:

2x×4.65×6.3= 2x\times4.65\times6.3=

Video Solution

Step-by-Step Solution

Upon observing the exercise note that we have two "regular" numbers and one number with a variable.
Given that this is a multiplication exercise, multiplying a number with a variable by a number without a variable doesn't present a problem.

In fact, it's important to remember that a variable attached to a number represents multiplication by itself, for example in this case: 2×x 2\times x
Therefore, we can apply the distributive property in order to separate the variable, and come back to it later.
Solve the exercise from left to right.

Solve the left exercise by breaking down the decimal number into an addition problem of a whole number and a decimal number as follows:

2×(4+0.65)= 2\times(4+0.65)=

Multiply 2 by each term inside of parentheses:

(2×4)+(2×0.65)= (2\times4)+(2\times0.65)=

Solve each of the expressions inside of the parentheses as follows:

8+1.3=9.3 8+1.3=9.3

We obtain the following exercise:

9.3×6.3= 9.3\times6.3=

Solve the exercise vertically in order to simplify the solution process.

It's important to be careful with the proper placement of the exercise, using the decimal point as an anchor.
Then we can proceed to multiply in order, first the ones digit of the first number by the ones digit of the second number. Then the tens digit of the first number by the ones digit of the second number, and so on.

9.3×6.3=58.59 9.3\\\times6.3\\=58.59

Don't forget to add the variable at the end resulting in the following answer:

58.59x 58.59x

Answer

58.59x 58.59x

Exercise #3

67x+87x+323x= \frac{6}{7}x+\frac{8}{7}x+3\frac{2}{3}x=

Video Solution

Step-by-Step Solution

Let's solve the exercise from left to right.

We will combine the left expression in the following way:

6+87x=147x=2x \frac{6+8}{7}x=\frac{14}{7}x=2x

Now we get:

2x+323x=523x 2x+3\frac{2}{3}x=5\frac{2}{3}x

Answer

523x 5\frac{2}{3}x

Exercise #4

2+a42= 2+\frac{a}{4}-2=

Video Solution

Step-by-Step Solution

We move the fraction to the beginning of the exercise and will place the rest of the exercise in parentheses to make solving the equation easier:

a4+(22)= \frac{a}{4}+(2-2)=

a4+0=a4 \frac{a}{4}+0=\frac{a}{4}

Answer

94 \frac{9}{4}

Exercise #5

5+3+4= -5+3+4=

Video Solution

Step-by-Step Solution

This exercise can be solved in order, but to make it easier, the associative property can be used

5+(3+4)= -5+(3+4)=

5+7= -5+7=

75=2 7-5=2

Answer

2 2

Exercise #6

Solve the following problem:

15.6×5.2x×0.3= 15.6\times5.2x\times0.3=

Video Solution

Step-by-Step Solution

Upon observing the exercise note that we have two "regular" numbers and one number with a variable.
Given that this is a multiplication exercise, multiplying a number with a variable by a number without a variable doesn't present a problem.

In fact, it's important to remember that a variable attached to a number represents multiplication by itself, for example in this case: 5.2×x 5.2\times x
Therefore, we can apply the distributive property in order to separate the variable, and come back to it later.
Proceed to solve the exercise from left to right.

Solve the left exercise vertically in order to avoid confusion as shown below:

     15.6×    5.2= 81.12 ~~~~~15.6 \\\times~~~~5.2 \\=~81.12

It's important to be careful with the correct placement of the exercise, where the decimal point serves as an anchor.
Then we can multiply in order, first the ones digit of the first number by the ones digit of the second number.
Next the tens digit of the first number by the ones digit of the second number, and so on.

We should obtain the following:

81.21×0.3= 81.21\times0.3=

Remember that:

0.3=0.30 0.3=\text{0}.30

Calculate:

24.336 24.336

Let's not forget to add the variable at the end resulting in the following answer:

24.336x 24.336 x

Answer

24.336x 24.336x

Exercise #7

34×23×214x= \frac{3}{4}\times\frac{2}{3}\times2\frac{1}{4}x=

Video Solution

Step-by-Step Solution

Let's begin by combining the simple fractions into a single multiplication exercise:

3×24×3×214x= \frac{3\times2}{4\times3}\times2\frac{1}{4}x=

Let's now proceed to solve the exercise in the numerator and denominator:

612×214x= \frac{6}{12}\times2\frac{1}{4}x=

Finally we'll simplify the simple fraction in order to obtain the following:

12×214x=118x \frac{1}{2}\times2\frac{1}{4}x=1\frac{1}{8}x

Answer

118x 1\frac{1}{8}x

Exercise #8

Solve the following expression:

10.1x+5.2x+2.4x= ? 10.1x+5.2x+2.4x=\text{ ?}

Video Solution

Step-by-Step Solution

The first step is factorising each of the terms in the exercise into a whole number and its remainder:

10x+0.1x+5x+0.2x+2x+0.4x= 10x+0.1x+5x+0.2x+2x+0.4x=

Now we'll combine only the whole numbers:

10x+5x+2x=15x+2x=17x 10x+5x+2x=15x+2x=17x

Next, we will calculate the remainder:

0.1x+0.2x+0.4x=0.3x+0.4x=0.7x 0.1x+0.2x+0.4x=0.3x+0.4x=0.7x

Finally, we are left with the following:

17x+0.7x=17.7x 17x+0.7x=17.7x

Answer

17.7x x

Exercise #9

Solve the following:

0.2x+8.6x+0.65x= 0.2x+8.6x+0.65x=

Video Solution

Step-by-Step Solution

According to the order of operations, we must solve the exercise from left to right:

0.2x+8.6x=8.8x 0.2x+8.6x=8.8x

We'll also break down 8.8 into a smaller addition exercise that will be easier for us to calculate:

8x+0.8x+0.65x= 8x+0.8x+0.65x=

Now we'll use the commutative property since the exercise only involves addition.

Let's focus on the leftmost addition exercise, remembering that:

0.8=0.80 0.8=0.80

Next, we'll calculate the exercise below:

0.80x+0.65x=1.45x 0.80x+0.65x=1.45x

Finally, we are left with the following:

8x+1.45x=9.45x 8x+1.45x=9.45x

Answer

9.45x 9.45x

Exercise #10

4a+(5a2)4a+10= 4a+(5a-2)-4a+10=

Video Solution

Step-by-Step Solution

According to the rules of the order of operations, we first eliminate the parentheses.

Remember that a positive times a positive will give a positive result, and a positive times a negative will give a negative result.

Therefore, we obtain:

4a+5a24a+10= 4a+5a-2-4a+10=

Now, we arrange the exercise in a more comfortable way using the substitution property:

4a+5a4a+102= 4a+5a-4a+10-2=

We solve the exercise from left to right, starting by adding the coefficients a:

4a+5a4a=9a4a=5a 4a+5a-4a=9a-4a=5a

Now we obtain:

5a+102=5a+8 5a+10-2=5a+8

Answer

5a+8 5a+8

Exercise #11

Solve the following problem:

356×556×13x= 3\frac{5}{6}\times5\frac{5}{6}\times\frac{1}{3}x=

Video Solution

Step-by-Step Solution

First, let's convert all mixed fractions to simple fractions:

3×6+56×5×6+56×13x= \frac{3\times6+5}{6}\times\frac{5\times6+5}{6}\times\frac{1}{3}x=

Let's solve the exercises with the eight fractions:

18+56×30+56×13x= \frac{18+5}{6}\times\frac{30+5}{6}\times\frac{1}{3}x=

236×356×13x= \frac{23}{6}\times\frac{35}{6}\times\frac{1}{3}x=

Since the exercise only involves multiplication, we'll combine all the numerators and denominators:

23×356×6×3x=805108x \frac{23\times35}{6\times6\times3}x=\frac{805}{108}x

Answer

805108x \frac{805}{108}x

Exercise #12

56x+78x+24x= \frac{5}{6}x+\frac{7}{8}x+\frac{2}{4}x=

Video Solution

Step-by-Step Solution

First, let's find a common denominator for 4, 8, and 6: it's 24.

Now, we'll multiply each fraction by the appropriate number to get:

5×46×4x+7×38×3x+2×64×6x= \frac{5\times4}{6\times4}x+\frac{7\times3}{8\times3}x+\frac{2\times6}{4\times6}x=

Let's solve the multiplication exercises in the numerator and denominator:

2024x+2124x+1224x= \frac{20}{24}x+\frac{21}{24}x+\frac{12}{24}x=

We'll connect all the numerators:

20+21+1224x=41+1224x=5324x \frac{20+21+12}{24}x=\frac{41+12}{24}x=\frac{53}{24}x

Let's break down the numerator into a smaller addition exercise:

48+524=4824+524=2+524=2524x \frac{48+5}{24}=\frac{48}{24}+\frac{5}{24}=2+\frac{5}{24}=2\frac{5}{24}x

Answer

2524x 2\frac{5}{24}x