When will there exist solutions to ax + (a+2)y = c?

  • Thread starter Shackleford
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In summary, the problem is that the equation does not always have the form ax + (a+2)y = c. However, with the help of a GCD algorithm, it is usually possible to find a solution.
  • #1
Shackleford
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Homework Statement



When will there exist solutions to ax + (a+2)y = c?

Homework Equations



GCD

The Attempt at a Solution



Of course, this is a linear Diophantine equation. I know that a solution will exist when gcd(a, (a+2)) | c.

gcd(a, (a+2)) = d ⇒ ∃ x,y ∈ ℤ ∋ xa + y(a+2) = d

a = 0(a+2) + a
a+2 = (a) + 2
a = β(2) + r
 
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  • #2
gcd(a, (a+2)) has a shorter expression.
Not sure what the last three lines are saying.
 
  • #3
mfb said:
gcd(a, (a+2)) has a shorter expression.
Not sure what the last three lines are saying.

I just started the algorithm for finding the GCD, but I don't think that I actually need to find an expression.

Hm. Well, I know that a and a+2 are both odd or even depending on a.
 
  • #4
Shackleford said:

Homework Statement



When will there exist solutions to ax + (a+2)y = c?

Homework Equations



GCD

The Attempt at a Solution



Of course, this is a linear Diophantine equation. I know that a solution will exist when gcd(a, (a+2)) | c.

gcd(a, (a+2)) = d ⇒ ∃ x,y ∈ ℤ ∋ xa + y(a+2) = d

a = 0(a+2) + a
a+2 = (a) + 2
a = β(2) + r

Have you forgotten to tell us whether or not a, c, x, y are positive (non-negative?) integers?
 
  • #5
Ray Vickson said:
Have you forgotten to tell us whether or not a, c, x, y are positive (non-negative?) integers?

Partially. a, b ∈ ℕ and x, y ∈ ℤ and 1 ≤ d ≤ min{a,b}.
 
  • #6
If you want to solve mu+nv = d when m and n are relatively prime, you should be able to find a specific solution with Bezout theorem. With that specific solution, you should be able to find a general solution (u,v) without too much difficulty.

The thing is that ax +(a+2) y = c has not that form, or at least not always. Why ? Mfb gave you a good hint. Think about it
 
  • #7
Shackleford said:
I just started the algorithm for finding the GCD, but I don't think that I actually need to find an expression.
I think you should, as the final expression is very easy. It is a bit like leaving 4+5 in a final answer. It is not wrong in terms of mathematics, but you should replace it by 9.
 

FAQ: When will there exist solutions to ax + (a+2)y = c?

1. What is the equation ax + (a+2)y = c?

The equation ax + (a+2)y = c is a linear equation that can be written in the form y = mx + b, where m is the slope and b is the y-intercept.

2. How do you solve ax + (a+2)y = c?

To solve ax + (a+2)y = c, you can use the method of substitution or elimination. In the method of substitution, you solve for one variable in terms of the other and then substitute the expression into the other equation. In the method of elimination, you manipulate the equations to eliminate one of the variables and then solve for the remaining variable.

3. What does it mean when there exist solutions to ax + (a+2)y = c?

When there exist solutions to ax + (a+2)y = c, it means that there are values for x and y that satisfy the equation. These values can be found by solving the equation using the methods mentioned in the previous question.

4. Can there be more than one solution to ax + (a+2)y = c?

Yes, there can be more than one solution to ax + (a+2)y = c. In fact, there can be an infinite number of solutions if the equation represents a line. This means that any point on the line can be a solution to the equation.

5. Is it possible for there to be no solutions to ax + (a+2)y = c?

Yes, it is possible for there to be no solutions to ax + (a+2)y = c. This happens when the equation represents parallel lines that never intersect. In this case, there is no point that satisfies both equations and therefore, no solution.

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