A math question. NEED ANSWER TONGIHT!!

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Max Shade IV

Max Shade IV

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Two numbers add up to eight (8) and if you cube each number (putting them to the third(3) power) you get twenty (20). What are the two numbers?

HELP NOW!!!!!​
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RE: A math question. NEED ANSWER TONGIHT!!

Weird... are you sure it is cubed? Because: 2^2+4^2=20. Unless the answer can be in fractional form.
 
RE: A math question. NEED ANSWER TONGIHT!!

I guess I could work it out for you. Do you mean that;

x + y = 8

And;

(x^3) + (y^3) = 20

?
 
RE: A math question. NEED ANSWER TONGIHT!!

What grade is your sister in!?! I was thinking there could be a negitive number, but then the negitive cubed would equal another negitive. Hmm...Hard...
 
No wonder, the answer is more complicated than you think. There are two answers (unless my math is totally messed up- it's late over here):

x = 4 + root(4.5)i

y = 4 - root(4.5)i

Or;

x = 4 - root(4.5)i

y = 4 + root(4.5)i

Where i is the imaginary number.

That's a horrible answer...
 
RE: A math question. NEED ANSWER TONGIHT!!

are you saying when you add the cubed results they equal 20 or each number automagically is equal to 20 when cubed?
 
RE: A math question. NEED ANSWER TONGIHT!!

Yeah...is that what you mean?
 
RE: A math question. NEED ANSWER TONGIHT!!

I assume he means that when added up, the cubed numbers equal 20. If they were 20 individually, this would mean that both numbers would in fact be the same. Henceforth;

x = cuberoot20

y = cuberoot20

And when added together, those do not make 8 so... ya.

Is this possibly a trick-question though? Imaginary numbers (or rather, complex numbers) only feature in the more advanced concepts of maths, so I'm wondering if it's supposed to be one of those questions you're not actually required to answer.

I am such a nerd.

:)
 
RE: A math question. NEED ANSWER TONGIHT!!

X + Y = 8
X^3 + Y^3 = 20


That's enough information to perform the substitution method, no?

So, some should probably perform the functions necessary to get X and Y by themselves.
 
Using the substitution method...

y = 8 - x

x^3 + y^3 = 20

x^3 + (8 - x)^3 = 20

Eh... I get stuck when working with exponents. Someone will have to take it from here. :[

Shawn out.
 
RE: A math question. NEED ANSWER TONGIHT!!

When you use the substitution method, you will eventually be able to reduce it to a quadratic equation. However, the equation cannot be solved unless you have an understanding of imaginary numbers.

Go ahead and try it yourself to see what I mean.
 
RE: A math question. NEED ANSWER TONGIHT!!

Ya what he said...[me no understandy]
 
RE: A math question. NEED ANSWER TONGIHT!!

Well, now that I think about it, the substitution method wouldn't work unless the second equation had coeffecients.

X + y = 8
X + y = 20^ -6

that wouldn't work since the same inputs can't have different outputs. So this problem is a trick question or was interpreted incorrectly.
 
RE: A math question. NEED ANSWER TONGIHT!!

Imperialdragon said:
Well, now that I think about it, the substitution method wouldn't work unless the second equation had coeffecients.

X + y = 8
X + y = 20^ -6

that wouldn't work since the same inputs can't have different outputs. So this problem is a trick question or was interpreted incorrectly.
Click to expand...

You guys are nerds :S

ID, the equation can't be solved :p
 
RE: A math question. NEED ANSWER TONGIHT!!

Here's what I get from this thread: An impossible question to answer and the it needed to be solved the night it was posted. Based on that, I'm going to close this. If by some chance you find an answer , bacon, just post it. :p

-Locked-
 
RE: A math question. NEED ANSWER TONGIHT!!

OH MY GOD I WISH YOU GUYS WOULD ACTUALLY READ MY POST.

I did indeed answer it.
 
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