QUOTIENT RULE OF EXPONENTS

Quotient Rule of Exponents :

When dividing exponential expression that have the same base, subtract the exponents.

aman = am-n

Example 1 :

x3x

Solution :

= x3x aman=am-n= x3-1= x2

Example 2 :

18c3-3c2

Solution :

= 18c3-3c2= -6c3-2= -6c

Example 3 :

9a3b5-3ab2

Solution :

9a3b5-3ab2= -3a3-1b5-2= -3a2b3

Example 4 :

-48c2d4-8cd

Solution :

= -48c2d4-8cd=6c2-1d4-1=6cd3

Example 5 :

22y6z82yz-7

Solution :

22y6z82yz-7=11y6-1z8+7=11y5z

Example 6 :

2x3-8x4

Solution :

= 2x3-8x41 4x3-41 4x-1

Example 7 :

xy7x3y4

Solution :

xy7x3y4= x1-3 y7-4= x-2 y3

Example 8 :

6x⋅ 3x⋅ x0

Solution :

Multiply the coefficients,

= 6x⋅ 3x⋅ x0

= (6 × 3)(x⋅ x⋅ x0)

By a⋅ an = am+n,

= 18(x5+5 ⋅ x0)

= 18(x10⋅ x0)

= 18x10

Example 9 :

(3st12)3

Solution :

(3st12)3

= 33s3(t12)3

= 27s3(t12)3

By (am)n = amn,

= 27s3t(12×3)

 27s3t36

Example 10 :

3m2n7m5

Solution :

3m2n7m5amn= amn(3)5m10n35m5amanam-n243m10-5n35= 243m5n35

Example 11 :

20x-427y28x-315y-5

Solution :

=20x-427y2 ÷ 8x-315y-5Multiply by the reciprocal of 8x-315y-5= 20x-427y2 × 15y-58x-3= 5x-49y2 × 5y-52x-3= 2518 x-4 . y-2 . y-5 . x3Combining like terms,= 2518 x-4 . x3 . y-5 . y-2= 2518 x-4+3 . y-5-2= 2518 x-1 . y-7= 2518 x-1y-7

Simplify the expression. Write your answer as a power.

Example 12 :

(75 ⋅ 73)/72

Solution :

= (75 ⋅ 73)/72

= 7(5 + 3) / 72

= 78/72

= 78 - 2

= 76

Example 12 :

(2.5)11 / (2.5)-x = (2.5)15

Solution :

(2.5)11 / (2.5)-x = (2.5)15

Using the quotient rule of exponents,

(2.5)11+x = (2.5)15

Since the bases are same, we can equate the powers.

11 + x = 15

x = 15 - 11

x = 4

11 + x 

Example 13 :

(-4/5)18 ÷ (-4/5)-x = (-4/5)14

Solution :

(-4/5)18 ÷ (-4/5)-x = (-4/5)14

(-4/5)18 + x = (-4/5)14

18 + x = 14

x = 14 - 18

x = -4

Example 14 :

The table shows the volumes of the largest gaint sequoia trees. Which tree has the greatest volume ? How much greater is its volume than the other tree ?

quotient-rule-p1

Solution :

General sherman is heavier than Washington tree.

= (5.25 x 104) / (4.785 x 104)

= (5.25 /4.785)

= 1.09

General sherman is 1.09 times heavier than Washington.

Example 15 :

A byte is a unit used to measure a computer’s memory. The table shows the numbers of bytes in several units of measure

quotient-rule-p2.png

a. How many kilobytes are in 1 terabyte?

b. How many megabytes are in 16 gigabytes?

c. Another unit used to measure a computer’s memory is a bit. There are 8 bits in a byte. How can you convert the number of bytes in each unit of measure given in the table to bits? Can you still use a base of 2? Explain.

Solution :

a. Number of kilobytes in 1 ter byte = 240 / 210

= 240 - 10

= 230

b. Number of bytes in 1 gigabyte = 230

Number of bytes in 16 gigabyte = 16(230)

Number of megabytes in 16 gigabyte = 16(230) / (220)

= 16(210)  

= 16384

c. 1 byte = 8 bits

To convert the number of bytes in each unit of measure given in the table to bits using a base of 2, we know that there are 8 bits in a byte. Therefore, to convert the number of bytes to bits, we can multiply the number of bytes by 8.

Example 16 :

Consider Cube A and Cube B.

quotient-rule-p3.png

a. Which property of exponents should you use to simplify an expression for the volume of each cube?

b. How can you use the Power of a Quotient Property to find how many times greater the volume of Cube B is than the volume of Cube A?

Solution :

a)

 Side length of cube A = 2x

Volume of cube A = 2x(2x)(2x)

= 8x3

 Side length of cube B = 6x

Volume of cube B = 6x(6x)(6x)

= 216x3

Using the product rule, we evaluate the volumes of each cubes.

b)  Volume of cube B is greater than volume of cube A.

Number of times = 216x3 / 8x3

= 27x3

Using quotient rule, we find the number of times.

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