Inverse Variation: Solve for y when x=5

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Homework Help Overview

The discussion revolves around an inverse variation problem where the relationship between y and the square of x is explored. The original poster presents a scenario where y varies inversely as the square of x, with a specific value given for y when x equals 1. The goal is to find the value of y when x equals 5.

Discussion Character

  • Conceptual clarification, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the correct formulation of the equation representing the inverse variation. There is confusion regarding the use of the equation y = k/x versus the correct form for inverse variation involving the square of x. Some participants attempt to verify potential answers by substituting values, while others question the steps taken in the reasoning process.

Discussion Status

The discussion is ongoing, with participants providing guidance on the correct interpretation of the problem. There is an acknowledgment of the need to clarify the equation used for inverse variation and to ensure that the square of x is correctly represented. Multiple interpretations of the problem setup are being explored.

Contextual Notes

Participants express uncertainty about the value of k and how to apply it in the context of the given problem. There is a focus on ensuring that the mathematical relationships are correctly understood before proceeding with calculations.

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Homework Statement



If y varies inversely as the square of x, and y = 1/8 when x = 1, find y when x = 5.

y = 8/25
y = 1/200

The Attempt at a Solution


The equation to find this is y=k/x, I know that. I've tried to plug in both given answers to see which ones matched but neither of them did. I'm not sure what to plug in for k or x. I just need someone to correctly set this up for me and I'll be able to solve it.
 
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amanda_ said:

Homework Statement



If y varies inversely as the square of x, and y = 1/8 when x = 1, find y when x = 5.

y = 8/25
y = 1/200


The Attempt at a Solution


The equation to find this is y=k/x, I know that.
No, it says that y varies inversely as the square of x.
amanda_ said:
I've tried to plug in both given answers to see which ones matched but neither of them did. I'm not sure what to plug in for k or x. I just need someone to correctly set this up for me and I'll be able to solve it.
 
amanda_ said:
If y varies inversely as the square of x


The Attempt at a Solution


The equation to find this is y=k/x[/QUOTE]

You'll need to try again, if the cube of x is x3, the square of x is?
 
rock.freak667 said:
You'll need to try again, if the cube of x is x3, the square of x is?

x2

So if I square 5 and cross multiply it's 8/25. Is that right?
 
Last edited:
amanda_ said:
x2

So if I square 5 and cross multiply it's 8/25. Is that right?

No, it's not. You skipped some steps. First, what is the equation? And you know that when x = 1, y = 1/8.
 

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