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# Differentiation watch

1. Just a little something I need clearing up...Finding out the value of x..

x^5/2 = 32

So I moved the exponent over, to make:

x = sprt 32^5

The answer is 4 but I obviously dont get that answer following my method - I thought that is how you deal with fractional exponents....?

I know it must be something simple I am forgetting :-(
2. (Original post by christinajane)
Just a little something I need clearing up...Finding out the value of x..

x^5/2 = 32

So I moved the exponent over, to make:

x = sprt 2^5

The answer is 4 but I obviously dont get that answer following my method - I thought that is how you deal with fractional exponents....?

I know it must be something simple I am forgetting :-(
If you have then this must mean that . Which is not .

Do you remember your indices laws?

If you have this is .
3. (Original post by christinajane)

x^5/2 = 32
Why don't you do it step by step?

is

So tex]x^{5/2} = (\sqrt{x})^5 = 32[/tex].

First step: move the 5 over. .

Now you're left with a simple equation: . Hence, squaring both sides: .

i.e: you need to square root four to get 2.
4. (Original post by Zacken)
If you have then this must mean that . Which is not .

Do you remember your indices laws?

If you have this is .

Hello Zacken,

I thought that when an exponent crosses the = sign it becomes a sqrt

like

x^2 = 4

so

x = sprt 4

x = 2

I thought the same thing happened with fractional exponents crossing the = sign..

so I thought in this case

x^5/2 = 32

x = sprt 32^5

on so on but I know its wrong....
5. (Original post by Zacken)
Why don't you do it step by step?

is

So tex]x^{5/2} = (\sqrt{x})^5 = 32[/tex].

First step: move the 5 over. .

Now you're left with a simple equation: . Hence, squaring both sides: .

i.e: you need to square root four to get 2.

Basically you just flip the fractional exponent when it crosses the = sign?

its these little things i keep forgetting!!
6. (Original post by christinajane)
Hello Zacken,

I thought that when an exponent crosses the = sign it becomes a sqrt

like

x^2 = 4

so

x = sprt 4

x = 2

I thought the same thing happened with fractional exponents crossing the = sign..

so I thought in this case

x^5/2 = 32

x = sprt 32^5

on so on but I know its wrong....
This is the rule: whenever you have an exponent crossing the = sign, you flip the the exponent over.

So if you move a 2 over, it becomes 1/2. i.e: means .

If you move over, it becomes 2. i.e: .

If you move over, it becomes .

If you move over, it becomes .
7. Thank you!!

Indices and surds get me everytime!! Its my most looked at chapters in the C1 book and on mymaths!!
8. (Original post by christinajane)
Thank you!!

Indices and surds get me everytime!! Its my most looked at chapters in the C1 book and on mymaths!!
It'll come with practice.

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