# mathematics equations concept

#### Ryan\$

##### Full Member
Hi guys! please I'm struggling that problem every day and I want to cut off that struggle totally.

lets assume I have equation like X^2+Y^2+Z^2=M^2 and didn't say anything about it, so it's in general.

afterwards we have conclude over specific case that case is satisfying the equation over specific parameter like Z=0 , then can I say that "specific case" is satisfying that equation: X^2+Y^2=M^2 ?! if so then why? I'm stuck in that struggle everyday, how we can assign specific parameter over specific case and then we say it's satisfying the general equation over specific parameter ! ?!

#### Dr.Peterson

##### Elite Member
Please don't try to generalize your questions. Instead, give a specific problem that you are actually working on, so we can see the real conditions under which these questions arise. Ask your question about such a specific problem, so that we can tell exactly what reason there is for each claim.

Until you cooperate in this way, you will not get satisfactory answers.

#### HallsofIvy

##### Elite Member
Yes, if you have a "general equation" of the form $$\displaystyle X^2+ Y^2+ Z^2= M^2$$, and Z=0, then, because Z=0, you can replace "Z" by "0" to get $$\displaystyle X^2+ Y^2+ 0^2= M^2$$ which is $$\displaystyle X^2+ Y^2= M^2$$. I'm not sure what you mean by "satisfying the general equation over specific parameter". Setting Z=0 changes the "general" equation to a less general equation. (I wouldn't say "specific" because X and Y can still be any value.)