EVALUATING EXPRESSIONS WITH POSITIVE AND NEGATIVE NUMBERS

Find :

Example 1 :

8 + - 5

Solution :

We use parentheses().

= 8 + (- 5)

By rule (+) . (-) = -, we get

= 8 - 3

= 3

Example 2 :

8 - - 5

Solution :

We use parentheses().

= 8 - (- 5)

By rule (-) . (-) = +, we get

= 8 + 5

= 13

Example 3 :

- 8 + - 5

Solution :

We use parentheses().

= (- 8) + (- 5)

Since the given numbers are having the same negative signs, we have to add them and put the negative sign.

= -13

Example 4 :

- 8 - - 5

Solution :

We use parentheses().

= (- 8) - (- 5)

By rule (-) . (-) = +, we get

= - 8 + 5

Since the given numbers are having the less positive and more negative signs, we have to subtract them and put the more negative sign.

= -3

Example 5 :

4 + - 9

Solution :

We use parentheses().

= 4 + (- 9)

By rule (+) . (-) = -, we get

= 4 - 9

= - 5

Example 6 :

4 - - 9

Solution :

We use parentheses().

= 4 - (- 9)

By rule (-) . (-) = +, we get

= 4 + 9

= 13

Example 7 :

- 4 + - 9

Solution :

We use parentheses().

= (- 4) + (- 9)

Since the given numbers are having the same negative signs, we have to add them and put the negative sign.

= -13

Example 8 :

- 4 - - 9

Solution :

We use parentheses ().

= (- 4) - (- 9)

By rule (-) . (-) = +, we get

= - 4 + 9

Since the given numbers are having the more positive and less negative signs, we have to subtract them and put the more positive sign.

= 5

Find :

Example 9 :

3 - - 2 + 4

Solution :

We use parentheses ().

= 3 - (- 2) + 4

Here the signs are multiplied.

By rule (-) . (-) = +, we get

= 3 + 2 + 4

= 9

Example 10 :

13 + - 5 - - 2

Solution :

We use parentheses ().

= 13 + (- 5) - (- 2)

Here the signs are multiplied.

By rule (-) . (-) = +, we get

= 13 + (- 5) + 2

By rule (+) . (-) = -, we get

= 13 - 5 + 2

= 8 + 2

= 10

Example 11 :

- 6 - - 4 + - 5

Solution :

We use parentheses ().

= (- 6) - (- 4) + (- 5)

Here the signs are multiplied.

By rule (-) . (-) = +, we get

= (- 6) + 4 + (- 5)

By rule (+) . (-) = -, we get

= (-6) + 4 - 5

= - 2 - 5

Since the negative signs, we have to add them and put the negative sign.

= - 7

Example 12 :

- 6 + - 1 - - 8

Solution :

We use parentheses ().

= (- 6) + (- 1) - (- 8)

= (- 6) + (- 1) + 8

= - 7 + 8

= 1

Example 13 :

5 - 12 - - 4

Solution :

We use parentheses ().

= 5 - 12 - (- 4)

= 5 - 12 + 4

= - 7 + 4

= - 3

Example 14 :

8 - 15 + - 11

Solution :

We use parentheses ().

= 8 - 15 + (- 11)

= 8 - 15 - 11

= 8 - 26

= - 18

Example 15 :

3 - - 1 - - 5

Solution :

We use parentheses ().

= 3 - (- 1) - (- 5)

= 3 + 1 + 5

= 9