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A student was supposed to substitute a certain value for x into the expression 2x^3. The student thought the expression was (2x)^3. If the student's answer was 384 greater then the correct answer, what value of x did the student use?

 

I hope this is the question!

So basically, I need help with the fact that you have a confusing equation...

I DONT EVEN GET THE QUESTION

HELP

 Nov 10, 2019
 #1
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Hi Sis!

 

That's how you post a question, alright!

 Nov 10, 2019
 #2
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Thank you, Shortie.

MagicKitten  Nov 10, 2019
 #4
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No fair you're six feet!!!

And two years older!

tommarvoloriddle  Nov 10, 2019
 #9
avatar+2490 
+1

How do you know? 

 

Wow, you are 6 feet already, you sure are healthy!

CalculatorUser  Nov 10, 2019
 #12
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+1

Never mind, you said "sis" 

 

 

That must mean that Magic Kitten is your sister!

CalculatorUser  Nov 10, 2019
 #13
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She's my 13-year-old sister who is SIX FREAKING FEET..

I'm 11 and 5'7...

 

 

My family is usually taller than average....

tommarvoloriddle  Nov 10, 2019
 #14
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Unfortunately, this idiot is my brother.

MagicKitten  Nov 10, 2019
 #15
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Wow.... you are TALL

 

 

I am 5'7'' too!
 

Except I am in 8th grade lol

CalculatorUser  Nov 10, 2019
 #17
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I'm in 8th grade.

 

I skipped a couple.

tommarvoloriddle  Nov 10, 2019
 #18
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So did I, I'm a Junior.

MagicKitten  Nov 10, 2019
 #23
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wow you guys all skipped grades.

 

Its so hard to skip grades in my area!
 

The only person EVER to skip a grade was a math prodigy who ACED the ACT in 5th grade, and also scores a NEARLY PERFECT on the AMC 8.

 

Also they do super good in mathcounts, placing top 20 in state.

CalculatorUser  Nov 10, 2019
 #25
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Welcome to Los angeles.

tommarvoloriddle  Nov 10, 2019
 #3
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+2

Ok, so this nimrod of a student was supposed to calculate 2 times x cubed. Instead, he computed 2x cubed. (2x)3 = 8x3

 

Now, we know that 2x^3 is 384 greater than the correct answer which is 8x^3.

 

8x^3 + 384 = 2x^3

-6x^3 = 384

x^3 = -64

x = -4

 Nov 10, 2019
edited by mathleteig  Nov 10, 2019
 #6
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I think that nimrod of a student could have been my brother...

 

Ahem Ahem

MagicKitten  Nov 10, 2019
 #7
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Thank you

MagicKitten  Nov 10, 2019
 #10
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SO mean, Jen...

 

T-T

tommarvoloriddle  Nov 10, 2019
 #5
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+2

What the question means is that:

 

when the student substituted a number for \(x\) in \((2x)^3\), the result was \(384\) larger than substituting for \(2x^3\).

 

So find X.

 

 

\(2x^3+384=(2x)^3\)

 

\(2x^3+384=8x^3\)

 

\(6x^3=384\)

 

\(x^3=64\)

 

\(x=4\)

 

The answer should be 4.

 Nov 10, 2019
 #8
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thank you

MagicKitten  Nov 10, 2019
 #11
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Wait, isn't it -4.

 Nov 10, 2019
 #16
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Let us ponder about that.

CalculatorUser  Nov 10, 2019
 #19
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By the way, I feel violated for how tall you guys are. At least I got taller than last year's pathetic 4'8". I'm 5'2" and in 7th grade.

 Nov 10, 2019
 #20
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Deleted

tommarvoloriddle  Nov 10, 2019
edited by tommarvoloriddle  Nov 10, 2019
edited by tommarvoloriddle  Nov 10, 2019
edited by tommarvoloriddle  Nov 10, 2019
edited by tommarvoloriddle  Nov 10, 2019
 #22
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My sisters Stole my laptop-

ran with it

somhow typed that

ran back

gave it back

and now

oof

 Nov 10, 2019
 #26
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for some reason I feel like you guys are a super hero family from the Incredibles.

 

except your sister has super speed

 

and maybe you have some super brains.

CalculatorUser  Nov 10, 2019
 #28
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My sister is more of an athletic girl but is like really smart.

 

 

I'm the super nerd- shes the popular outgoing nerd.

 

 

Her favorite game is Torment her younger Brother with the help of my younger sister.

tommarvoloriddle  Nov 10, 2019
edited by tommarvoloriddle  Nov 10, 2019
 #27
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I'm smarter then my idiot brother!!!

:<

And im like a popular nerd???? #mybrosaidthis

 

I don't know..

 

I take Jujitsu...

 Nov 10, 2019
 #29
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the thing is, \(\frac{1}{3}\) of my school is nerds.

 

Literally, everybody has like an IQ over \(9000\)

 

Everybody goes tryhard, and its so hard to be at the top.

 

 

I dream of going to this school, called IMSA.

 

Its one of the top ten highschools in the nation!
 

You have to apply, and it is SUPER competitive.

 

 

The academics there, are, HARD.

 

you are REQUIRED to take AMC 10, its like part of the curricilum. The math classes are competition based. meaning, everyday, you day mathounts type math.

CalculatorUser  Nov 10, 2019
 #30
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I go to an all-girls private school.

 

ScHOlaRsHiP!!!

 

The food is great...

Lol

MagicKitten  Nov 10, 2019
 #31
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cool!

CalculatorUser  Nov 10, 2019
 #32
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CalculatorUser, what school district do you go to?

 Nov 10, 2019
 #33
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Indian Prairie 204 in Illinois

CalculatorUser  Nov 10, 2019
edited by CalculatorUser  Nov 10, 2019
edited by CalculatorUser  Nov 10, 2019
 #35
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Oof- Los Angeles Girl here!

MagicKitten  Nov 10, 2019
 #34
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I don't know....

 Nov 10, 2019

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