Solve this System of Equations: .5= (x-40)/(x-y) and .5=(40-y)/(x-y)

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Homework Help Overview

The discussion revolves around solving a system of equations represented by .5= (x-40)/(x-y) and .5=(40-y)/(x-y). Participants are exploring methods to manipulate these equations to find values for x and y.

Discussion Character

  • Exploratory, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants discuss various methods for solving the equations, including substitution and elimination. Some express difficulty in isolating variables, while others suggest multiplying to eliminate fractions. There are also questions about the independence of the equations and the implications of their relationships.

Discussion Status

The conversation includes attempts to clarify the problem and explore different solving techniques. Some participants have provided partial manipulations of the equations, while others have noted potential issues with the independence of the equations, leading to the possibility of infinite solutions. There is no explicit consensus on the best approach or final outcome.

Contextual Notes

Participants are working under the constraints of a homework forum, where complete solutions are discouraged. There is a noted concern about providing answers rather than guiding through the reasoning process.

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Homework Statement



Solve for x and y

.5= (x-40)/(x-y) and .5=(40-y)/(x-y)

Homework Equations





The Attempt at a Solution



I have been trying to solve this system of equations for hours and I can't seem to get it. Can anyone please give it a shot and see what they get? I'm sure I am overlooking a simple mistake. Thanks
 
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.5= (x-40)/(x-y) and .5=(40-y)/(x-y)

You need to first isolate a single variable for the substitution method, or put the equations in the standard form for elimination. I chose to use the substitution method (and what better variable to chose then Y to double check with a calc). I will show you my work for the first equation.

.5 = (x-40)/(x-y)

//Multiply both sides of the left eq. by the denominator of the right to cancel the denominators/fractions.
.5(x-y) = (x-40)

//Distribute out the .5(x-y)
.5x-.5y = x-40

//Subtract a .5x from both sides
-.5y = .5x - 40

//Finally divide both sides by a -.5 to isolate the variable y, resulting in:

y = (.5x-40)/(-.5)

Here is what I got for the two in terms of Y.

Y1= (.5x-40)/(-.5)

Y2= (40+.5x)/(.5)

Surely you know where to go from here? (Substitution, Elimination, Matrice, or a graphing calculator etc)

How do your steps look? Perhaps if you show your steps up until, and after this point we can figure out where you are going wrong.

Cheers
 
Last edited:
Personally, I would get rid of all fractions by multiplying each equation by 2(x- y).

That gives x- y= 2(x- 40) and x- y= 2(40- y). Multiplying those out, x- y= 2x- 80 or x+ y= 80, and x- y= 80- 2y or x+ y= 80. Those two equations are the same so the original equations were not "independent". There are an infinite number of solutions. Given any x, (x, y)= (x, 80- x) is a solution (except (40, 40) for which x- y= 0 and the original equation makes no sense).
 
HallsofIvy said:
Personally, I would get rid of all fractions by multiplying each equation by 2(x- y).

That gives x- y= 2(x- 40) and x- y= 2(40- y). Multiplying those out, x- y= 2x- 80 or x+ y= 80, and x- y= 80- 2y or x+ y= 80. Those two equations are the same so the original equations were not "independent". There are an infinite number of solutions. Given any x, (x, y)= (x, 80- x) is a solution (except (40, 40) for which x- y= 0 and the original equation makes no sense).

Again with giving out the answer! I thought that wasn't allowed in the homework forum!
 

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