Stuck on a stupid math proof...

[GT1999]

I'm half way through this induction proof (Discrete Math). My roomate, who's an ACS major (I'm telecom, which is 1/2 ACS), who has had Calculus I, II, and III cannot get it either. I'm stuck.


I need to make 1/7(8^k+1 -1) + (k+1) equal to 1/7(8^[(k+1)+1] -1)

Assume k >= 1.

If I don't get any replies I think I'll live, I have the other problem done... and this one is partially done, but this is the step I'm lost on. Stupid algebra -- I know there's a way, because he said all problems he gives us are solvable.

 

[GT1999]

Linked

 

[Paul Ma]

um, they're not equal, that's your problem.
you're off by a factor of 8 somewhere.

 

[onelin]

Are you sure what you gave us is correct? It doesn't work for k=1 or k=2.

btw: calc I, II, III won't do JACK for you on proofs... I've taken them. Discrete, Math Thought (that's what it is at my college anyway), Abstract Algebra are where it's at for that...

 

[GT1999]

I did the whole problem, maybe it will show my idiotic mistake somewhere. At least I hope.

The whole problem

Edit: He did say everything he would ever give us is solvable, so I know it has to be my error. He might've said just tests, but I doubt it. This is obviously homework. The only thing HE gave me was the very top part, obviously.. the rest is my work and could have an error on it.

Edit #2: Maybe that (k+1) is supposed to be a (8k + 1). My brain is fried. :-/

 

[TuxDave]

The line that starts with

LHS = ....

Is incorrect. It should state.

LHS = 1 + ... + 8^(K+1) = 1/7(8^(K+1)-1)+8^(K+1)

 

[upsciLLion]

Originally posted by: TuxDave
The line that starts with

LHS = ....

Is incorrect. It should state.

LHS = 1 + ... + 8^(K+1) = 1/7(8^(K+1)-1)+8^(K+1)

Ding ding ding. We have a winner.

 

[MAME]

dingggggggg

 

[MithShrike]

Bah I don't now sh!t about math. Barely got through geometry. Hell, I thought those proofs were hard.

 

[GT1999]

Yes, I forgot to update, I got it, and it was my fault ;-)