power and exponents
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We know how to calculate the expression 5 x 5.
This expression can be written in a shorter way using something called exponents.
5 × 5
= 5²
An expression that represents repeated multiplication of the same factor is called a power.
The number 5 is called the base, and the number 2 is called the exponent.
The exponent corresponds to the number of times the base is used as a factor.
Here are some examples :-
3¹
3 to the first power3
4²
4 to the second power or 4 squared
4 × 4
5³
5 to the third power or 5 cubed
5 × 5 × 5
2^6
2 to the power of six
=2 × 2 × 2 × 2 × 2 × 2
If two powers have the same base then we can multiply the powers. When we multiply two powers we add their exponents.
The rule:
x^a × x^b
= x^a+b
Examples :
4² + 4²
= 4²+²
= 4 ⁴
If two powers have the same base then we can divide the powers. When we divide powers we subtract their exponents.
The rule :
x⁴/x²
= x⁴-²
= x²
Example :
5⁴/5²
= 5⁴-²
= 5²
A negative exponent is the same as the reciprocal of the positive exponent.
x^-a
= 1/x^a
Example :
(4)-²
= 1/4²
When you raise a product to a power you raise each factor with a power.
(x × y)^a
Example :
(2x)⁴
= 2⁴ × 6⁴
= 16x⁴
The rule for the power of a power and the power of a product can be combined into the following rule :
( x^a × y^b )^z = x^a×z × y^b×z
Example :
(x² × y²)³
= x²×³ × x²×³
x^6 × x^6
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An expression that represents repeated multiplication of the same factor is called apower. The number 5 is called the base, and the number 2 is called the exponent. The exponentcorresponds to the number of times the base is used as a factor.
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