Examples with solutions for Addition and Subtraction of Directed Numbers: Solving the problem

Exercise #1

Solve the following equation:

(8)+(+12)= ? (-8)+(+12)=\text{ ?}

Video Solution

Step-by-Step Solution

First, let's remember the rule:

+(+x)=+x +(+x)=+x

Now let's write the exercise in the following way:

8+12= -8+12=

We'll draw a number line and place minus 8 on it, then move 12 steps to the right:

-1-1-1-4-4-4-3-3-3-2-2-2-5-5-5-6-6-6-8-8-8-7-7-7444000111222333

Therefore:

8+12=4 -8+12=4

Answer

4 4

Exercise #2

Solve the following problem

(+6)(+11)= (+6)-(+11)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

(+x)=x -(+x)=-x

Now let's write the exercise in the appropriate form:

611= 6-11=

We'll locate the number 6 on the number line and from there we'll move 11 steps to the left:

111-2-2-2-1-1-1000-3-3-3-4-4-4666222333444555-5-5-5

The answer is minus 5.

Answer

5 -5

Exercise #3

(8)(13)= (-8)-(-13)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

(x)=+x -(-x)=+x

Now let's write the exercise in the appropriate form:

8+13= -8+13=

We'll use the substitution law and solve:

138=5 13-8=5

Answer

5 5

Exercise #4

(10)(+13)= (-10)-(+13)=

Video Solution

Step-by-Step Solution

Let's locate -10 on the number line and move 13 steps to the left.

Let's note that our result is a negative number:

000-10-10-10-13

Let's remember the rule:

(+x)=x -(+x)=-x

Now let's write the exercise in the appropriate form and solve it:

1013=23 -10-13=-23

Answer

23 -23

Exercise #5

(8)+(12)= (-8)+(-12)=

Video Solution

Step-by-Step Solution

Let's locate -8 on the number line and move 12 steps to the left.

Let's note that our result is a negative number:

000-8-8-8-12

Let's remember the rule:

Now let's write the exercise in the appropriate form and solve it:

812=20 -8-12=-20

Answer

20 -20

Exercise #6

Solve the following expression:

(+8)+(+12)= ? (+8)+(+12)=\text{ ?}

Video Solution

Step-by-Step Solution

Let's add 8 to the number line and move 12 steps to the right.

Note that our result is a positive number:

Now solve the following exercise:

8+12=20 8+12=20

Answer

20 20

Exercise #7

Solve the following expression:

(x)(6x)= ? (-x)-(-6x)=\text{ ?}

Video Solution

Step-by-Step Solution

Note the following rule:

(x)=+x -(-x)=+x

Now let's rewrite the exercise as follows:

x+6x= -x+6x=

Then, we will write -x on the number line and move 6 steps to the right:

5X5X5X000-X-X-X

Therefore, the solution is:

x+6x=5x -x+6x=5x

Answer

5x 5x

Exercise #8

Simplify the following expression:

(x)(+3x)= ? (-x)-(+3x)=\text{ ?}

Video Solution

Step-by-Step Solution

Note the following rule:

(+x)=x -(+x)=-x

Now let's write the exercise in the following way:

x3x= -x-3x=

We'll add negative x x to the values on the number line and move 3 steps to the left:

-X-X-X-4X-4X-4X-3X-3X-3X-2X-2X-2X

Therefore, the solution is:

x3x=4x -x-3x=-4x

Answer

4x -4x

Exercise #9

Simplify the following expression:

(x)+(5x)= (-x)+(-5x)=

Video Solution

Step-by-Step Solution

Note the following rule:

+(x)=x +(-x)=-x

Now let's write the exercise in the following way:

x5x= -x-5x=

We'll add negative x x to the number line and move 5 steps to the left:

-X-X-X-4X-4X-4X-3X-3X-3X-2X-2X-2X-5X-5X-5X-6X-6X-6X

Therefore, the solution is:

x5x=6x -x-5x=-6x

Answer

6x -6x

Exercise #10

(+x)+(+3x)= ? (+x)+(+3x)=\text{ ?}

Video Solution

Step-by-Step Solution

First let's remember the rule:

+(+x)=+x +(+x)=+x

Now let's write the exercise in the following way:

x+3x= x+3x=

We'll can then add x x to the number line values and move 3 steps to the right:

2X2X2X3X3X3X4X4X4X1X1X1X

Therefore, the solution is:

x+3x=4x x+3x=4x

Answer

4x 4x

Exercise #11

(+x)(+4x)= ? (+x)-(+4x)=\text{ ?}

Video Solution

Step-by-Step Solution

First, let's remember the rule:

(+x)=x -(+x)=-x

Now let's write the exercise in the following way:

x4x= x-4x=

We'll add x x to the number line and go 4 steps to the left:

-X-X-X000XXX-2X-2X-2X-3X-3X-3X

Therefore the solution is:

x4x=3x x-4x=-3x

Answer

3x -3x

Exercise #12

(18)+(68)= (-\frac{1}{8})+(-\frac{6}{8})=

Video Solution

Step-by-Step Solution

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

  • Step 1: Add the numerators of the fractions.
  • Step 2: Keep the common denominator for the result.
  • Step 3: Simplify if necessary and confirm with answer choices.

Let's work through the solution step-by-step:

Step 1: Add the numerators.

The expression is 18+68 -\frac{1}{8} + -\frac{6}{8} .

The numerators are 1-1 and 6-6. Adding these gives:

1+(6)=16=7-1 + (-6) = -1 - 6 = -7.

Step 2: Write the result over the common denominator.

Since the denominator is 88, the fraction becomes 78 -\frac{7}{8} .

Step 3: Verify and finalize the result.

The result 78-\frac{7}{8} matches one of the multiple-choice options.

Therefore, the solution to the problem is 78 -\frac{7}{8} .

Answer

78 -\frac{7}{8}

Exercise #13

(x)+(+2x)= (-x)+(+2x)=

Video Solution

Step-by-Step Solution

To solve this problem, follow these steps:

  • Step 1: Identify and combine the like terms in the expression (x)+(+2x)(-x) + (+2x).
  • Step 2: Focus on the coefficients of xx. The term x-x can be seen as 1x-1x, and the term +2x+2x has a coefficient of +2+2.
  • Step 3: Add the coefficients of these like terms: 1+2=1-1 + 2 = 1.

Now, let's simplify:

Starting with the expression:
(x)+(+2x)=1x+2x(-x) + (+2x) = -1x + 2x.
Combine the coefficients: (1+2)x=1x(-1 + 2)x = 1x.

This simplifies to xx, as 1x1x is simply xx.

Therefore, the solution to the problem is x x .

Answer

x x

Exercise #14

(+567)(69)= (+567)-(-69)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

(x)=+x -(-x)=+x

Now let's write the exercise in the appropriate form:

567+69= 567+69=

Let's solve the exercise vertically:

567+69636 567\\+69\\636

Answer

636 636

Exercise #15

Solve the following expression:

(+8)+(4.5)= ? (+8)+(-4.5)=\text{ ?}

Video Solution

Step-by-Step Solution

First we need to locate the number 8 on the number line and move 4.5 steps to the left from it:

000888

Remember the rule:

+(x)=x +(-x)=-x

Now let's rewrite the problem in the appropriate form and solve:

84.5=3.5 8-4.5=3.5

Answer

3.5 3.5

Exercise #16

Solve the following exercise:

(17)(77)= (-\frac{1}{7})-(-\frac{7}{7})=

Step-by-Step Solution

Let's position minus 17 \frac{1}{7} on the number line and move one step to the right, since 77=11=1 \frac{7}{7}=\frac{1}{1}=1

We should note that our result is a positive number:

000+1

Let's remember the rule:

(x)=+x -(-x)=+x

Now let's write the exercise in the appropriate form and solve it:

17+1=67 -\frac{1}{7}+1=\frac{6}{7}

Answer

67 \frac{6}{7}

Exercise #17

Solve the following expression:

(+100)(+1.01)= ? (+100)-(+1.01)=\text{ ?}

Video Solution

Step-by-Step Solution

Note the following rule:

(+x)=x -(+x)=-x

Now let's rewrite the exercise as follows:

1001.01= 100-1.01=

We should note that we are subtracting between two positive numbers, meaning we will obtain a positive result.

Therefore:

1001.0198.99 100\\-1.01\\98.99

Answer

98.99 98.99

Exercise #18

(0.21)+(0.79)= (-0.21)+(-0.79)=

Video Solution

Step-by-Step Solution

Using the following rule:

+(x)=x +(-x)=-x

Let's rewrite the exercise as seen below:

0.210.79= -0.21-0.79=

Since we are subtracting from a negative number, the result will be negative.

Therefore:

0.210.791.00 -0.21\\-0.79\\-1 .00

Answer

1 -1

Exercise #19

(+0.18)+(+0.88)= (+0.18)+(+0.88)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

+(+x)=+x +(+x)=+x

Now let's write the exercise in the following way:

0.18+0.88= 0.18+0.88=

Since we are multiplying two positive numbers, the result will be positive.

Therefore:

0.18+0.881.06 0.18\\+0.88\\1.06

Answer

1.06 1.06

Exercise #20

(+215)(3050)= (+2\frac{1}{5})-(-\frac{30}{50})=

Video Solution

Step-by-Step Solution

Let's remember the rule:

(x)=+x -(-x)=+x

Now let's write the exercise in the following way:

215+3050= 2\frac{1}{5}+\frac{30}{50}=

We'll reduce the fraction 3050 \frac{30}{50} by 10

215+35=245 2\frac{1}{5}+\frac{3}{5}=2\frac{4}{5}

Answer

245 2\frac{4}{5}