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razzy02

Could someone please explain this to me?

Reply 1

Kevin De Bruyne

Original post by razzy02

Could someone please explain this to me?

What is 81^(1/4), first of all? How can you work out what it is?

Same logic for the 25 term

Then see how to put that knowledge together

Reply 2

razzy02

Original post by SeanFM

What is 81^(1/4), first of all? How can you work out what it is?

Same logic for the 25 term

Then see how to put that knowledge together

So 81^(1/4) is 3, and 25 ^ (-1/2) is 50 and then I would multiply them together.
Is this correct?

Reply 3

KaylaB

Original post by razzy02

So 81^(1/4) is 3, and 25 ^ (-1/2) is 50 and then I would multiply them together.
Is this correct?

Not quite for the part in bold.

If, like you correctly calculated,

81^{\frac{1} {4}} = \sqrt[4] {81} = 3

Then, first of all what would

25^{\frac{1} {2}}

be?

Reply 4

razzy02

Original post by KaylaB

Not quite for the part in bold.

If, like you correctly calculated,

81^{\frac{1} {4}} = \sqrt[4] {81} = 3

Then, first of all what would

25^{\frac{1} {2}}

be?

It would be 5

Reply 5

KaylaB

Original post by razzy02

It would be 5

Correct

, and what does a negative power mean?

Reply 6

razzy02

Original post by KaylaB

Correct

, and what does a negative power mean?

You see that's where I begin to struggle with the question! would I have to flip the fraction upside down?

Reply 7

KaylaB

Original post by razzy02

You see that's where I begin to struggle with the question! would I have to flip the fraction upside down?

Ah I see! For negative indices, it means you do 1 over the x value without the negative sign. It doesn't make much sense when I'm typing it, so I apologise, hopefully this image will show you what I mean

So in the same way as the graphic above. How else can

25^{-\dfrac{1} {2}}

be written?

Reply 8

razzy02

Original post by KaylaB

So in the same way as the graphic above. How else can

25^{-\dfrac{1} {2}}

be written?

Thank you so much!! So it would be 1/25^1/2?

Reply 9

KaylaB

Original post by razzy02

Thank you so much!! So it would be 1/25^1/2?

No problem :hat2:

Yes it would be :h:

So, if we already know what

25^{\frac{1} {2}}

is equal to, then what is

25^{-\frac{1} {2}} = \dfrac{1} {25^\frac{1} {2}}

Reply 10

razzy02

Original post by KaylaB

No problem :hat2:

Yes it would be :h:

So, if we already know what

25^{\frac{1} {2}}

is equal to, then what is

25^{-\frac{1} {2}} = \dfrac{1} {25^\frac{1} {2}}

1/5!!

Reply 11

KaylaB

Original post by razzy02

1/5!!

Yes! Well done! :clap2:

So finally, can you now tell me what

81^{\frac{1} {4}} \times 25^{-\frac{1} {2}}

is equal to? :holmes:

Reply 12

razzy02

Original post by KaylaB

Yes! Well done! :clap2:

So finally, can you now tell me what

81^{\frac{1} {4}} \times 25^{-\frac{1} {2}}

is equal to? :holmes:

That would be 3 x 1/5 = 0.6 xx
Thank you so much for all your help!!!

Reply 13

KaylaB

Original post by razzy02

That would be 3 x 1/5 = 0.6 xx
Thank you so much for all your help!!!

That's correct, good job! :clap2:

Glad that I could be of assistance :h:

Reply 14

keeleighgeorge

to work out something to the power of 1/4 you simply find the square root, then find the square root again. eg 81=9=3.

when finding out a negative power you need to make it positive by flipping the fraction so there its 25 to the power of -1/2 changes to just 1/2 meaning square root of 25 which is 5.

Then multiply 3 and 5 to get the final answer.