Examples with solutions for The Distributive Property for 7th Grade: Using variables

Exercise #1

8x(5+y)= 8x(5+y)=

Video Solution

Step-by-Step Solution

To solve this problem, we will simplify the expression 8x(5+y) 8x(5+y) using the distributive property.

  • Step 1: Recognize the expression as 8x 8x multiplied by two terms inside a parenthesis, 5 5 and y y .
  • Step 2: Apply the distributive property: 8x(5+y)=8x5+8xy 8x(5+y) = 8x \cdot 5 + 8x \cdot y .
  • Step 3: Compute each multiplication:
    - 8x5=40x 8x \cdot 5 = 40x
    - 8xy=8xy 8x \cdot y = 8xy
  • Step 4: Combine the results from the multiplication steps: 40x+8xy 40x + 8xy .

Thus, the simplified expression of 8x(5+y) 8x(5+y) is 40x+8xy 40x + 8xy .

Comparing with provided answer choices, the correct solution corresponds to choice 1:40x+8xy 1: 40x + 8xy .

Answer

40x+8xy 40x+8xy

Exercise #2

2a+3b6(a2b)= 2a+3b-6(a-2b)=

Video Solution

Step-by-Step Solution

To solve this problem, we'll apply the distributive property and combine like terms.

  • Step 1: Apply the distributive property.
    We have the expression 2a+3b6(a2b)2a + 3b - 6(a - 2b). Let's distribute the 6-6 across the terms inside the parentheses:
    6(a2b)=6a+(6)(2b)=6a+12b-6(a - 2b) = -6 \cdot a + (-6) \cdot (-2b) = -6a + 12b.
  • Step 2: Combine like terms.
    Now substitute 6a+12b-6a + 12b back into the expression:
    2a+3b6a+12b2a + 3b - 6a + 12b.
    Combine the like terms, 2a2a and 6a-6a, and 3b3b and 12b12b:
    (2a6a)+(3b+12b)=4a+15b(2a - 6a) + (3b + 12b) = -4a + 15b.

Therefore, the simplified expression is 4a+15b-4a + 15b, which matches choice 2.

Answer

4a+15b -4a+15b

Exercise #3

4a(ab)+3b(ab)= 4a(a-b)+3b(a-b)=

Video Solution

Step-by-Step Solution

To solve this problem, we'll expand and simplify the given expression 4a(ab)+3b(ab) 4a(a-b) + 3b(a-b) by applying the distributive property.

Let's go through the steps:

  • Step 1: Apply the distributive property to the first term.
    4a(ab)=4aa4ab=4a24ab 4a(a-b) = 4a \cdot a - 4a \cdot b = 4a^2 - 4ab
  • Step 2: Apply the distributive property to the second term.
    3b(ab)=3ba3bb=3ab3b2 3b(a-b) = 3b \cdot a - 3b \cdot b = 3ab - 3b^2
  • Step 3: Combine the results from Step 1 and Step 2.
    Combine like terms: 4a24ab+3ab3b2=4a2ab3b2 4a^2 - 4ab + 3ab - 3b^2 = 4a^2 - ab - 3b^2

Therefore, the simplified form of the expression is 4a2ab3b2 4a^2 - ab - 3b^2 .

Among the given choices, the correct answer is:

4a2ab3b2 4a^2-ab-3b^2

Answer

4a2ab3b2 4a^2-ab-3b^2

Exercise #4

a+3(4a6)= a+3(4a-6)=

Video Solution

Step-by-Step Solution

To solve the problem of simplifying the expression a+3(4a6) a+3(4a-6) , follow these detailed steps:

  • Step 1: Distribute 3 across the terms in the parentheses.
    This means multiplying 3 with each term inside: 4a 4a and 6-6 .
  • Step 2: Perform the multiplication:
    3×4a=12a 3 \times 4a = 12a
    3×(6)=18 3 \times (-6) = -18
  • Step 3: Combine the distributed terms with a a :
    Start with the given expression, a+12a18 a + 12a - 18 .
  • Step 4: Simplify by combining like terms:
    Add the coefficients of a a : a+12a=13a a + 12a = 13a .
  • Step 5: Form the final expression:
    The simplified expression is 13a18 13a - 18 .

Therefore, the solution to the problem is 13a18 13a - 18 , which corresponds to choice 2.

Answer

13a18 13a-18

Exercise #5

6x(2x+3y)+12x2= 6x(-2x+3y)+12x^2=

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Apply the distributive property to expand the expression.
  • Step 2: Simplify the expression by combining like terms.

Now, let's work through each step:

Step 1: Apply the distributive property to 6x(2x+3y) 6x(-2x + 3y) .
This gives us:
6x(2x)+6x(3y)=12x2+18xy 6x \cdot (-2x) + 6x \cdot (3y) = -12x^2 + 18xy .

Step 2: Add this result to 12x2 12x^2 :
12x2+18xy+12x2-12x^2 + 18xy + 12x^2.

Combine like terms:
12x2+12x2-12x^2 + 12x^2 cancels out, leaving 18xy 18xy .

Therefore, the simplified form of the expression is 18xy 18xy .

Answer

18xy 18xy

Exercise #6

a(a+b)ab(5a6b)= a(a+b)-ab(5a-6b)=

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Distribute the first part of the expression a(a+b) a(a+b) .
  • Step 2: Distribute the second part of the expression ab(5a6b)-ab(5a-6b).
  • Step 3: Combine the expressions obtained from steps 1 and 2.
  • Step 4: Combine like terms.

Now, let's work through each step:

Step 1: Distribute a(a+b) a(a+b) :
a(a+b)=aa+ab=a2+ab a(a+b) = a \cdot a + a \cdot b = a^2 + ab .

Step 2: Distribute ab(5a6b)-ab(5a-6b):
ab(5a6b)=ab5a+(ab)(6b)=5a2b+6ab2-ab(5a-6b) = -ab \cdot 5a + (-ab) \cdot (-6b) = -5a^2b + 6ab^2 .

Step 3: Combine the results obtained from these two distributions:
(a2+ab)+(5a2b+6ab2)(a^2 + ab) + (-5a^2b + 6ab^2).

Step 4: Combine like terms:
The expression is already simplified as all terms are unique.
Therefore, the simplified form of the expression is a2+ab5a2b+6ab2 a^2 + ab - 5a^2b + 6ab^2 .

Therefore, the solution to the problem is a2+ab5a2b+6ab2 a^2 + ab - 5a^2b + 6ab^2 .

Answer

a2+ab5a2b+6ab2 a^2+ab-5a^2b+6ab^2

Exercise #7

(7x+3)×(10+4)=238 (7x+3)\times(10+4)=238

Video Solution

Step-by-Step Solution

We begin by solving the addition exercise in the right parenthesis:

(7x+3)+14=238 (7x+3)+14=238

We then multiply each of the terms inside of the parentheses by 14:

(14×7x)+(14×3)=238 (14\times7x)+(14\times3)=238

Following this we solve each of the exercises inside of the parentheses:

98x+42=238 98x+42=238

We move the sections whilst retaining the appropriate sign:

98x=23842 98x=238-42

98x=196 98x=196

Finally we divide the two parts by 98:

9898x=19698 \frac{98}{98}x=\frac{196}{98}

x=2 x=2

Answer

2

Exercise #8

(9+17x)×(6+1)=420 (9+17x)\times(6+1)=420

Calculate a X

Video Solution

Step-by-Step Solution

We begin by solving the addition exercise in the right parenthesis:

(9+17x)×7=420 (9+17x)\times7=420

We then multiply each of the terms inside the parentheses by 7:

(9×7)+(17x×7)=420 (9\times7)+(17x\times7)=420

We continue by solving each of the exercises inside of the parentheses:

63+119x=420 63+119x=420

Following this we rearrange the sections whilst maintaining the appropriate sign:

119x=42063 119x=420-63

119x=357 119x=357

Finally we divide the two parts by 119:

119119x=357119 \frac{119}{119}x=\frac{357}{119}

x=3 x=3

Answer

3

Exercise #9

(a+3a)×(5+2)=112 (a+3a)\times(5+2)=112

Calculate a a

Video Solution

Step-by-Step Solution

We begin by solving the two exercises inside of the parentheses:

4a×7=112 4a\times7=112

We then divide each of the sections by 4:

4a×74=1124 \frac{4a\times7}{4}=\frac{112}{4}

In the fraction on the left side we simplify by 4 and in the fraction on the right side we divide by 4:

a×7=28 a\times7=28

Remember that:

a×7=a7 a\times7=a7

Lastly we divide both sections by 7:

a77=287 \frac{a7}{7}=\frac{28}{7}

a=4 a=4

Answer

4

Exercise #10

A building is 21 meters high, 15 meters long, and 14+30X meters wide.

Express its volume in terms of X.

(14+30X)(14+30X)(14+30X)212121151515

Step-by-Step Solution

We use a formula to calculate the volume: height times width times length.

We rewrite the exercise using the existing data:

21×(14+30x)×15= 21\times(14+30x)\times15=

We use the distributive property to simplify the parentheses.

We multiply 21 by each of the terms in parentheses:

(21×14+21×30x)×15= (21\times14+21\times30x)\times15=

We solve the multiplication exercise in parentheses:

(294+630x)×15= (294+630x)\times15=

We use the distributive property again.

We multiply 15 by each of the terms in parentheses:

294×15+630x×15= 294\times15+630x\times15=

We solve each of the exercises in parentheses to find the volume:

4,410+9,450x 4,410+9,450x

Answer

4410+9450x 4410+9450x

Exercise #11

Look at the rectangle in the figure.

What is its area?

Video Solution

Step-by-Step Solution

We know that the area of a rectangle is equal to its length multiplied by its width.

We begin by writing an equation with the available data.

(4x+x2)×(3x+8+5x) (4x+x^2)\times(3x+8+5x)

Next we use the distributive property to solve the equation.

(4x×3x)+(4x×8)+(4x×5x)+(x2×3x)+(x2×8)+(x2×5x)= (4x\times3x)+(4x\times8)+(4x\times5x)+(x^2\times3x)+(x^2\times8)+(x^2\times5x)=

We then solve each of the exercises within the parentheses:

12x2+32x+20x2+3x3+16x2+5x3= 12x^2+32x+20x^2+3x^3+16x^2+5x^3=

Finally we add up all the coefficients of X squared and all the coefficients of X cubed and we obtain the following:

48x2+8x3+32x 48x^2+8x^3+32x

Answer

8x3+28x2+44x 8x^3+28x^2+44x

Exercise #12

Gerard plans to paint a fence 7X meters high and 30X+4 meters long.

Gerardo paints at a rate of 7 m² per half an hour.

Choose the expression that represents the time it takes for Gerardo to paint one side of the fence.

30X+430X+430X+47X7X7X

Video Solution

Step-by-Step Solution

In order to solve the exercise, we first need to know the total area of the fence.

Let's remember that the area of a rectangle equals length times width.

Let's write the exercise according to the given data:

7x×(30x+4) 7x\times(30x+4)

We'll use the distributive property to solve the exercise. That means we'll multiply 7x by each term in the parentheses:

(7x×30x)+(7x×4)= (7x\times30x)+(7x\times4)=

Let's solve each term in the parentheses and we'll get:

210x2+28x 210x^2+28x

Now to calculate the painting time, we'll use the formula:

7m212hr=14m2hr \frac{7m^2}{\frac{1}{2}hr}=14\frac{m^2}{hr}

The time will be equal to the area divided by the work rate, meaning:

210x2+28x14 \frac{210x^2+28x}{14}

Let's separate the exercise into addition between fractions:

210x214+28x14= \frac{210x^2}{14}+\frac{28x}{14}=

We'll reduce by 14 and get:

15x2+2x 15x^2+2x

And this is Isaac's work time.

Answer

15x2+2x 15x^2+2x hours