Real_jenn
Badges: 15
Rep:
?
#1
Report Thread starter 4 years ago
#1
"4n^2/3 = 8^-1/3
Find the value of N"

I know the answer is 1/4 but how did you get the answer ?

Thanks sooo much in advance 😊😊
0
reply
NotNotBatman
Badges: 20
Rep:
?
#2
Report 4 years ago
#2
(Original post by Real_jenn)
"4n^2/3 = 8^-1/3
Find the value of N"

I know the answer is 1/4 but how did you get the answer ?

Thanks sooo much in advance 😊😊
I didn't get 1/4, I got root2/32
0
reply
Raiden10
Badges: 17
Rep:
?
#3
Report 4 years ago
#3
(Original post by Real_jenn)
"4n^2/3 = 8^-1/3
Find the value of N"

I know the answer is 1/4 but how did you get the answer ?

Thanks sooo much in advance 😊😊
Multiplication and exponentiation are functions. They have inverses on the positive integers. You need to apply the inverse functions to both sides.

Your question makes no sense without brackets though. It's like asking, what is 2^3^4=? It could be 4096, or over 2 million million million million.
0
reply
Real_jenn
Badges: 15
Rep:
?
#4
Report Thread starter 4 years ago
#4
(Original post by NotNotBatman)
I didn't get 1/4, I got root2/32
That was the answer in the book ,it just didn't explain why that was the answer
0
reply
Real_jenn
Badges: 15
Rep:
?
#5
Report Thread starter 4 years ago
#5
(Original post by Raiden10)
Multiplication and exponentiation are functions. They have inverses on the positive integers. You need to apply the inverse functions to both sides.

Your question makes no sense without brackets though. It's like asking, what is 2^3^4=? It could be 4096, or over 2 million million million million.
Okay,you know what I mean now.Insert brackets if that eases your heart
0
reply
NotNotBatman
Badges: 20
Rep:
?
#6
Report 4 years ago
#6
(Original post by Real_jenn)
That was the answer in the book ,it just didn't explain why that was the answer
rearrange to find n.
Divide both sides by 4
do you now where to go from here?
0
reply
Raiden10
Badges: 17
Rep:
?
#7
Report 4 years ago
#7
(Original post by Real_jenn)
Okay,you know what I mean now.Insert brackets if that eases your heart
Well, 4x(n^(2/3)) = 8^-(1/3),
(4x(n^2))/3 = 8^-(1/3)
4x((n^2)/3) = (8^-1)/3
((4xn)^2)/3 = 8^(-1/3)
(4xn)^(2/3) = (8^-1)/3,

which of those do you mean? do you understand why those are all valid interpretations of expression?

Inserting brackets eases my heart. *AND* it makes the question make sense.

For example, if I said, "Bobby only reads fantasy, Jimmy only reads Manga. Today, Bobby hit Jimmy with his book. Did Bobby hit Jimmy with (A) a fantasy book or (B) a manga book?",

This could be interpreted as Bobby hit Jimmy with Bobby's book, OR Bobby hit Jimmy with Jimmy's book. It's ambiguous.

"Bobby (hit Jimmy) with his book " = Fantasy
"Bobby hit (Jimmy with his book) " = Manga

Some people use a convention where + (or its inverse, -) is applied first, followed by multiplication x (or its inverse, /), followed by exponentiation (or its inverse (nth root).

This gives (4xn)^(2/3)=8^(-1/3)

This gives (4n)^(2/3)=1/(8^(1/3))=1/2

Thus giving 4n=(1/2)^(3/2)=((1/2)^3)x((1/2)^(1/2))=(1/8)x(1/sqrt(2))

Therefore giving n=(1/32)x(1/sqrt(2))
0
reply
Real_jenn
Badges: 15
Rep:
?
#8
Report Thread starter 4 years ago
#8
(Original post by Raiden10)
Well, 4x(n^(2/3)) = 8^-(1/3),
(4x(n^2))/3 = 8^-(1/3)
4x((n^2)/3) = (8^-1)/3
((4xn)^2)/3 = 8^(-1/3)
(4xn)^(2/3) = (8^-1)/3,

which of those do you mean? do you understand why those are all valid interpretations of expression?

Inserting brackets eases my heart. *AND* it makes the question make sense.

For example, if I said, "Bobby only reads fantasy, Jimmy only reads Manga. Today, Bobby hit Jimmy with his book. Did Bobby hit Jimmy with (A) a fantasy book or (B) a manga book?",

This could be interpreted as Bobby hit Jimmy with Bobby's book, OR Bobby hit Jimmy with Jimmy's book. It's ambiguous.

"Bobby (hit Jimmy) with his book " = Fantasy
"Bobby hit (Jimmy with his book) " = Manga

Some people use a convention where + (or its inverse, -) is applied first, followed by multiplication x (or its inverse, /), followed by exponentiation (or its inverse (nth root).

This gives (4xn)^(2/3)=8^(-1/3)

This gives (4n)^(2/3)=1/(8^(1/3))=1/2

Thus giving 4n=(1/2)^(3/2)=((1/2)^3)x((1/2)^(1/2))=(1/8)x(1/sqrt(2))

Therefore giving n=(1/32)x(1/sqrt(2))

That question was precisely copied from a authorised edexcell book no brackets were inserted,but I understand you so thank you for the answer,very well explained.
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

Regarding Ofqual's most recent update, do you think you will be given a fair grade this summer?

Yes (206)
33.28%
No (413)
66.72%

Watched Threads

View All