Is this mathematically correct? If x is a variable, then x+1=x since x can be anything (1 Viewer)

[anjalika9923]

I don't know how to word it any other way. Here's a pic of how I used it in a proof

Thanks

 

[SylviaB]

wow

 

[cossine]

"If x is a variable then can x+1 = x be anything?"

For assignments you can change the value. If x+1 = x is an equation however you will end up with 0 = 1 which is not correct.

In the case of assignment you should have single term on the LHS. So instead of x+1 = x the assignment would be x = x-1

For assignment normally := is used instead of = to avoid confusion with equations.

 

[Everwinter]

You cannot, did you or the question itself defined the variable p before? like p is an integer or something? If you didn't then define it, if you did, you can either define p+1 as P, where P is also an integer (or whatever you defined it as), you can also use := sign, which means something is defined to be equal to something, where you can do let p := p + 1, which translated as let p defined to be equal to p + 1. To clarify things, you can write next to it (since integer is closed under +, -, x, ÷) this part is not necessary for the actual exam.
I would like to see the full question and the solution to it, because it may not make sense to chuck this in the middle.

 

[anjalika9923]

You cannot, did you or the question itself defined the variable p before? like p is an integer or something? If you didn't then define it, if you did, you can either define p+1 as P, where P is also an integer (or whatever you defined it as), you can also use := sign, which means something is defined to be equal to something, where you can do let p := p + 1, which translated as let p defined to be equal to p + 1. To clarify things, you can write next to it (since integer is closed under +, -, x, ÷) this part is not necessary for the actual exam.
I would like to see the full question and the solution to it, because it may not make sense to chuck this in the middle.

It's part of an induction question. I introduced p and q and specifically said "let p, q=the variable number of coins needed" and p, q are positive integers. I think I will just change the way I've set it out so it's similar to how you do divisibility induction questions eg. x=5A+5B, and at the end you get x=5C where C=A+B (something like that). Thanks

 

[CM_Tutor]

It's part of an induction question. I introduced p and q and specifically said "let p, q=the variable number of coins needed" and p, q are positive integers. I think I will just change the way I've set it out so it's similar to how you do divisibility induction questions eg. x=5A+5B, and at the end you get x=5C where C=A+B (something like that). Thanks

In that case, I agree with @Everwinter and suggest that this should be something like


So, can be written in the form where , as required.