Laws of Exponent
Laws of Exponents
Here are the Laws (explanations follow): Law | Example | x1 = x | 61 = 6 | x0 = 1 | 70 = 1 | x-1 = 1/x | 4-1 = 1/4 | | | xmxn = xm+n | x2x3 = x2+3 = x5 | xm/xn = xm-n | x6/x2 = x6-2 = x4 | (xm)n = xmn | (x2)3 = x2×3 = x6 | (xy)n = xnyn | (xy)3 = x3y3 | (x/y)n = xn/yn | (x/y)2 = x2 / y2 | x-n = 1/xn | x-3 = 1/x3 | And the law about Fractional Exponents: | | |
Laws Explained
The first three laws above (x1 = x, x0 = 1 and x-1 = 1/x) are just part of the natural sequence of exponents. Have a look at this example: Example: Powers of 5 | | .. etc.. | | | 52 | 1 × 5 × 5 | 25 | | 51 | 1 × 5 | 5 | | 50 | 1 | 1 | | 5-1 | 1 ÷ 5 | 0.2 | | 5-2 | 1 ÷ 5 ÷ 5 | 0.04 | | | .. etc.. | | |
You will see that positive, zero or negative exponents are really part of the same pattern, i.e. 5 times larger (or smaller) depending on whether the exponent gets larger (or smaller).
The law that xmxn = xm+n
With xmxn, how many times will you end up multiplying "x"? Answer: first "m" times, then by another "n" times, for a total of "m+n" times.
Example: x2x3 = (xx)(xxx) = xxxxx = x5
So, x2x3 = x(2+3) = x5
The law that xm/xn = xm-n
Like the previous example, how many times will you end up multiplying "x"? Answer: "m" times, then reduce that by "n" times (because you are dividing), for a total of "m-n" times.
Example: x4/x2 = (xxxx) / (xx) = xx = x2 = x4-2
(Remember that x/x = 1, so every time you see an x "above the line" and one "below the line" you can cancel them out.)
This law can also show you why x0=1 :
Example: x2/x2 = x2-2 = x0 =1
The law that (xm)n = xmn
First you multiply x "m" times. Then you have to do that "n" times, for a total of m×n times.
Example: (x3)4 = (xxx)4 = (xxx)(xxx)(xxx)(xxx) = xxxxxxxxxxxx = x12
So (x3)4 = x3×4 = x12
The law that (xy)n = xnyn
To show how this one works, just think of re-arranging all the "x"s and "y" as in this example:
Example: (xy)3 = (xy)(xy)(xy) =
Here are the Laws (explanations follow): Law | Example | x1 = x | 61 = 6 | x0 = 1 | 70 = 1 | x-1 = 1/x | 4-1 = 1/4 | | | xmxn = xm+n | x2x3 = x2+3 = x5 | xm/xn = xm-n | x6/x2 = x6-2 = x4 | (xm)n = xmn | (x2)3 = x2×3 = x6 | (xy)n = xnyn | (xy)3 = x3y3 | (x/y)n = xn/yn | (x/y)2 = x2 / y2 | x-n = 1/xn | x-3 = 1/x3 | And the law about Fractional Exponents: | | |
Laws Explained
The first three laws above (x1 = x, x0 = 1 and x-1 = 1/x) are just part of the natural sequence of exponents. Have a look at this example: Example: Powers of 5 | | .. etc.. | | | 52 | 1 × 5 × 5 | 25 | | 51 | 1 × 5 | 5 | | 50 | 1 | 1 | | 5-1 | 1 ÷ 5 | 0.2 | | 5-2 | 1 ÷ 5 ÷ 5 | 0.04 | | | .. etc.. | | |
You will see that positive, zero or negative exponents are really part of the same pattern, i.e. 5 times larger (or smaller) depending on whether the exponent gets larger (or smaller).
The law that xmxn = xm+n
With xmxn, how many times will you end up multiplying "x"? Answer: first "m" times, then by another "n" times, for a total of "m+n" times.
Example: x2x3 = (xx)(xxx) = xxxxx = x5
So, x2x3 = x(2+3) = x5
The law that xm/xn = xm-n
Like the previous example, how many times will you end up multiplying "x"? Answer: "m" times, then reduce that by "n" times (because you are dividing), for a total of "m-n" times.
Example: x4/x2 = (xxxx) / (xx) = xx = x2 = x4-2
(Remember that x/x = 1, so every time you see an x "above the line" and one "below the line" you can cancel them out.)
This law can also show you why x0=1 :
Example: x2/x2 = x2-2 = x0 =1
The law that (xm)n = xmn
First you multiply x "m" times. Then you have to do that "n" times, for a total of m×n times.
Example: (x3)4 = (xxx)4 = (xxx)(xxx)(xxx)(xxx) = xxxxxxxxxxxx = x12
So (x3)4 = x3×4 = x12
The law that (xy)n = xnyn
To show how this one works, just think of re-arranging all the "x"s and "y" as in this example:
Example: (xy)3 = (xy)(xy)(xy) =