Уроки математики и физики (RU + UA)

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вторник, 8 ноября 2016 г.

Lesson 7. Exponentiation

In the expression  xa  the quantity  x  is called the base, a  is the exponent of the power, and  xa  is the  ath  power of  a  or  x  raised to the  ath  power.

EXAMPLE:

The exponents of the quantities  63 24 55  and  32  are, respectively, 3, 4, 5  and  2.

Square number

When a whole number is multiplied by itself, we get a square number.

EXAMPLE:

3 × 3 = 9

We write this as 32 (3 squared)

32= 3 × 3 = 9
52 = 5 × 5 = 25

Cube number

When a whole number is multiplied by itself 3 times, we get a cube number.

EXAMPLE:

2 × 2 × 2 = 8

We write this as 23 (2 squared)

13 = 1 × 1 × 1 = 1

(This is 1 cubed. Sometimes we say 1 to the power 3)

EXAMPLES:

3 × 3  is written as  32 
(power 2)

3 × 3 × 3  is written as  33 
(power 3)

3 × 3 × 3 × 3  is written as  34 
(the power 4 means multiply 4 lots of 3 together)

For 34 we say ‘3 to the power 4’
‘3 to the power 5’ is 35 which means 

3 × 3 × 3 × 3 × 3

Numbers written using powers are said to be in index form

EXAMPLES:

81 written index form is 34
(because 3 × 3 × 3 × 3 × 3 = 81)

20 written index form is 22 × 5
(because 2 × 2 × 5 = 20)

Tasks to the lesson 7
Other lessons:
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