# Proof by inductionWatch

Announcements
Thread starter 1 month ago
#1
I keep getting stuck on inductive step! Any tips ?!?
0
reply
Thread starter 1 month ago
#2
How did he get from line 1 to 2 on the inductive step ?! What did he factor out
0
reply
1 month ago
#3
(k+1)!
0
reply
1 month ago
#4
(Original post by MM2002)
How did he get from line 1 to 2 on the inductive step ?! What did he factor out
Leave the -1 alone and factorise the leftover two terms by taking out (k+1)!
0
reply
Thread starter 1 month ago
#5
(Original post by RDKGames)
Leave the -1 alone and factorise the leftover two terms by taking out (k+1)!
Am I left with this expression then (k+1)! [ -1 +(k+1)]
0
reply
Thread starter 1 month ago
#6
(Original post by Idg a damn)
(k+1)!
I did that also. I still can not get the k+2 part
0
reply
1 month ago
#7
(Original post by MM2002)
Am I left with this expression then (k+1)! [ -1 +(k+1)]
No.

(k+1)! + (k+1)(k+1)! = (k+1)! [ 1 + (k+1)]
0
reply
Thread starter 1 month ago
#8
(Original post by RDKGames)
No.

(k+1)! + (k+1)(k+1)! = (k+1)! [ 1 + (k+1)]
I don't see how the one is positive?
0
reply
1 month ago
#9
(Original post by MM2002)
I don't see how the one is positive?
Expand the brackets then to verify that it must be +1 and not -1.

If its -1 then expanding back will give you -(k+1)! which is not a term we have.
0
reply
Thread starter 1 month ago
#10
(Original post by RDKGames)
Expand the brackets then to verify that it must be +1 and not -1.

If its -1 then expanding back will give you -(k+1)! which is not a term we have.
But, by factoring I don't see why it turns to -1
0
reply
1 month ago
#11
(Original post by MM2002)
How did he get from line 1 to 2 on the inductive step ?! What did he factor out
(k+1)! - 1 + (k+1)(k+1)!
= [(k+1)! + (k+1)(k+1)!] - 1
=[ { (k+1)! } { (1) + (k+1) } ] - 1
= [(k+1)! (k+2)] - 1
= (k+2)! - 1

does that help?
0
reply
1 month ago
#12
(Original post by MM2002)
But, by factoring I don't see why it turns to -1
It doesnt ??

You seem very confused.

I have just shown you the factorisation, and then you asked why its +1 and not -1, and now you ask how it turns into -1... which it doesnt.

If you are talking about the -1 at the end of the expression on its own, then this is the same -1 I told you to ignore in my first post. We dont manipulate it at all here.
Last edited by RDKGames; 1 month ago
0
reply
Thread starter 1 month ago
#13
(Original post by shreytib)
(k+1)! - 1 + (k+1)(k+1)!
= [(k+1)! + (k+1)(k+1)!] - 1
=[ { (k+1)! } { (1) + (k+1) } ] - 1
= [(k+1)! (k+2)] - 1
= (k+2)! - 1

does that help?
AMAZING!! Finally, understand how all the values come about. Thanks sooo much! Also, any tips on solving the inductive step?
0
reply
Thread starter 1 month ago
#14
(Original post by RDKGames)
It doesnt ??

You seem very confused.

I have just shown you the factorisation, and then you asked why its +1 and not -1, and now you ask how it turns into -1... which it doesnt.

If you are talking about the -1 at the end of the expression on its own, then this is the same -1 I told you to ignore in my first post. We dont manipulate it at all here.
That clears things up. I was thinking about the -1 you told me ignore.
0
reply
X

Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### University open days

• University of East Anglia
PGCE Open day Postgraduate
Tue, 3 Mar '20
• University of Bradford
Postgraduate Open day/Evening Postgraduate
Tue, 3 Mar '20
• Queen's University Belfast
Postgraduate LIVE Masters & PhD Study Fair Postgraduate
Wed, 4 Mar '20

### Poll

Join the discussion

#### Do you get study leave?

Yes- I like it (499)
59.76%
Yes- I don't like it (43)
5.15%
No- I want it (237)
28.38%
No- I don't want it (56)
6.71%

View All
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.