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# Credit Maths Sequences trouble watch

1. Hello.

As you may know the exam starts soon, ive already started revising but in Credit maths ive got a problem with one topic:sequences. Ive done a few past papers and those questions trip me up the most. They are for a minor amount of marks, but i want to get it right.Here's an example:

1,3,5,7,

The first odd number can be expressed as 1=1²-0²
The second odd number can be expressed as 3=2²-1²
the third odd number can be expressed as 5=3²-2²

a. Express the 4th odd number in this form
b. Express the number 19 in this form
c. Write down a formula for the nth odd number and simplify this expression

thats the question, i hope someone can help me. the first 2 parts i get as they are easy , it the last part, anything about the nth term, i go clueless.

it would be appreciated if someone could tell me how to handle these questions, i dont want an answer as ive got it , i want to know how to handle these questions.

Thanks
2. well let's go through this
the first odd number can be expressed as the number one squared- the number one less than one squared ie 0 squared
the second odd number can be expressed as the number two - the number one squared less than two squared ie 1 squared
if this continues the nth odd number can be expressed as the number n squared- the number one less than n squared ie n^2-(n-1)^2 which you can simplify

essentially look for the pattern in the terms they give you
3. (Original post by roar558)
well let's go through this
the first odd number can be expressed as the number one squared- the number one less than one squared ie 0 squared
the second odd number can be expressed as the number two - the number one squared less than two squared ie 1 squared
if this continues the nth odd number can be expressed as the number n squared- the number one less than n squared ie n^2-(n-1)^2 which you can simplify

essentially look for the pattern in the terms they give you
I don't get that

Here ive got this:

1=1²-0²
3=2²-1
5=3²-2²
7=4²-3²

what next , how do i find the pattern?
4. (Original post by animelover123)
I don't get that

Here ive got this:

1=1²-0²
3=2²-1
5=3²-2²
7=4²-3²

what next , how do i find the pattern?
the first term, let's call that N1=1^2-0^2
N2=2^2 - 1 ^2
N3=3^2 - 2^2
You should be able to tell by looking that what happens is that Nn=n^2 - (n-1)^2
5. (Original post by roar558)
the first term, let's call that N1=1^2-0^2
N2=2^2 - 1 ^2
N3=3^2 - 2^2
You should be able to tell by looking that what happens is that Nn=n^2 - (n-1)^2
Why minus 1?

Sorry I'm being a pain, but i really don't get this.

Never I'm i ge the minus 1 part now

I didn't know you could substitute the odd numbers on the left with the n thingy
6. (Original post by animelover123)
Why minus 1?

Sorry I'm being a pain, but i really don't get this.

Never I'm i ge the minus 1 part now

I didn't know you could substitute the odd numbers on the left with the n thingy
It's essentially what it's asking you to do when you're asked for the nth term, to write the equation in terms of n
7. (Original post by roar558)
It's essentially what it's asking you to do when you're asked for the nth term, to write the equation in terms of n
Thanks a lot for the help, and MAths meant to be one of my strongest subjects...Its these and indicies i cant do, everything else seem to be fine

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