Examples with solutions for Multiplication and Division of Signed Mumbers: Using order of arithmetic operations

Exercise #1

(7+4):(9)= -(-7+4):(-9)=

Video Solution

Step-by-Step Solution

First, let's solve what's in the parentheses:

7+4=3 -7+4=-3

Now the expression we got:

(3):(9)= -(-3):(-9)=

Let's remember the rule:

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

Therefore:

(3)=3 -(-3)=3

Now the expression we got is:

3:(9)= 3:(-9)=

Let's write the expression as a simple fraction:

+39= \frac{+3}{-9}=

Note that we are dividing a positive number by a negative number, so the result must be a negative number:

+= \frac{+}{-}=-

Let's break down the 9 into a multiplication problem:

33×3= -\frac{3}{3\times3}=

Let's reduce the 3 in both the numerator and denominator of the fraction and we get:

13 -\frac{1}{3}

Answer

13 -\frac{1}{3}

Exercise #2

3.5:7+14= -3.5:-7+14=

Video Solution

Step-by-Step Solution

Let's solve the exercise from left to right.

We'll write the division problem as a simple fraction in the following way:

3.57+14= \frac{-3.5}{-7}+14=

Let's note that we are dividing a negative number by a negative number, so the result will necessarily be a positive number:

=+ \frac{-}{-}=+

We'll break down 7 into a multiplication problem:

3.53.5×2+14= \frac{3.5}{3.5\times2}+14=

We'll reduce the 3.5 in both the numerator and denominator of the fraction and get:

12+14=1412 \frac{1}{2}+14=14\frac{1}{2}

Answer

+1412 +14\frac{1}{2}

Exercise #3

400:(713+10)= -400:(-7-13+10)=

Video Solution

Step-by-Step Solution

First, let's solve the expression in parentheses from left to right:

713=20 -7-13=-20

20+10=10 -20+10=-10

Now the expression we have is:

400:10= -400:-10=

Let's note that we are dividing two negative numbers, so the result must be a positive number:

=+ \frac{-}{-}=+

Therefore:

40010=40 \frac{400}{10}=40

Answer

+40 +40

Exercise #4

7:49:+14:(3+2)= -7:-49:+14:(-3+2)=

Video Solution

Step-by-Step Solution

First, let's solve what's inside the parentheses:

3+2=1 -3+2=-1

Now the exercise looks like this:

7:49:+14:1= -7:-49:+14:-1=

Let's treat the exercise as division between two simple fractions:

(7:49):(+14:1)= (-7:-49):(+14:-1)=

749:+141= \frac{-7}{-49}:\frac{+14}{-1}=

Let's look at the simple fraction on the left side.

Since we are dividing a negative number by a negative number, the result will be positive.

Let's break down 49 into a multiplication exercise:

77×7= \frac{7}{7\times7}=

Let's reduce the 7 in the numerator and denominator and we get:

17 \frac{1}{7}

Now the exercise we got is:

17:+141= \frac{1}{7}:\frac{+14}{-1}=

Let's convert the division to multiplication, don't forget to switch between numerator and denominator:

17×1+14= \frac{1}{7}\times\frac{-1}{+14}=

Let's reduce to one exercise:

1×17×14=1+98 \frac{1\times-1}{7\times14}=\frac{-1}{+98}

Since we are dividing a negative number by a positive number, the result will be negative:

:+= -:+=-

Therefore we get:

198 -\frac{1}{98}

Answer

198 -\frac{1}{98}

Exercise #5

12:6(8+4)= -12:-6\cdot(-8+4)=

Video Solution

Step-by-Step Solution

Let's first solve the expression in parentheses:

8+4=4 -8+4=-4

Now the expression is:

12:6×4= -12:-6\times-4=

Let's solve the expression from left to right.

We'll write the division as a simple fraction like this:

126= \frac{-12}{-6}=

Note that we are dividing between two negative numbers, so the result must be a positive number:

=+ \frac{-}{-}=+

Therefore:

126=2 \frac{12}{6}=2

Now the expression we got is:

2×4= 2\times-4=

Note that we are multiplying a positive number by a negative number, so the result must be a negative number:

+×= +\times-=-

Therefore the result is:

2×4=8 2\times-4=-8

Answer

8 -8