Fractions GCSE HELP

OP

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Reply 2

olipal

1

\left( \dfrac{27}{8} \right)^{-\frac{2}{3}}

? Think about what the negative sign means before the indice, and also the fact that

a^{\frac{2}{3}} \equiv (a^{\frac{1}{3}})^3

.

(edited 12 years ago)

Reply 3

OP

Original post by olipal

(\dfrac{27}{8})^{-\frac{2}{3}}

? Think about what the negative sign means before the indice, and also the fact that

a^{\frac{2}{3}} \equiv (a^{\frac{1}{3}})^3

.

Does it mean like you put it into a fraction?

Reply 4

olipal

1

Original post by iPad User

Does it mean like you put it into a fraction?

Well (and I'll give another example using letters not to completely give the game away), note that

a^{-b} \equiv \dfrac{1}{a^b}

.

Reply 5

OP

Yeh I already knew that but its because its in a fraction it kind of threw me... I dont get it when theres a fraction? How do you do it?

Reply 6

Well, OP, what does the negative power suggest?

Reply 7

Original post by iPad User

Yeh I already knew that but its because its in a fraction it kind of threw me... I dont get it when theres a fraction? How do you do it?

Well do you understand basic factions, such as

4^{1/2}

(edited 12 years ago)

Reply 8

OP

Original post by proud nd luvin it

Well, OP, what does the negative power suggest?

That you put it in a fraction over one.

Reply 9

OP

Original post by proud nd luvin it

Well do you understand basic factions, such as

4^{1/2}

Yes that means, square root 4, then do it to the power of 1.

Reply 10

olipal

1

If you have a fraction to the power of a negative number, flip the numerator and the denominator around before calculating the power (and of course, remove the negative sign). Think of

\left(\dfrac{a}{b} \right)^{-c}

as being

\dfrac{1}{\left(\dfrac{a}{b} \right)^{c}}

.

You shoud know what happens when you divide a number by a fraction, right?

(edited 12 years ago)

Reply 11

Original post by iPad User

That you put it in a fraction over one.

Right, so just for the minute, let's ignore the negative sign, waht would you normally do with the power?

Reply 12

bloomingblossoms

basically, because it's(-) you have to flip the fraction over so it's effectively 1/(27/8) which = 8/27. Then you must cube root 8/27 which will give 2/3 and then square 2/3 which = 4/9- i hope this helps :smile:

(edited 12 years ago)

Reply 13

Original post by iPad User

Yes that means, square root 4, then do it to the power of 1.

Right, so

(27/8)^{-2/3} = (8/27)^{2/3}

Reply 14

and also, using an indices rule, you should know that

(a/b)^{c} = (a^{c} / b^{c})

Reply 15

OP

Original post by proud nd luvin it

Right, so just for the minute, let's ignore the negative sign, waht would you normally do with the power?

I think I get it now, so first we do 1 over (27 over 8) now we flip it because its a minus to make 1 over 8 over 27, now we find the cube root, because this is the bottom number of the fraction (3), which give us 2 over 3, we now square them both because two is on top, giving us 4 over 9?!

Reply 16

01010000 01001010

11

You could have worked that one out on your iPad, right?

Reply 17