Year 12s: what will be the first way you research your future options? >>

Year 12s: what will be the first way you research your future options? >>

Year 12s: what will be the first way you research your future options? >>

Binomial expansion question

(1+x)ⁿ ; if n is a positive integer, the expansion is finite and exact

What does the word 'exact' mean in this context?

Also how do you determine the range of values of x for which an expansions is valid? Eg..

i) (1+2x)³
ii) (1-3x)^1/3

Exact means that it is exact ... it is the actual expansion and gives the actual value

When it is not a positive integer it is an infinite expansion and will not give an exact value

Look at the range of values for which x is valid
That's the same range of values for which 2x or -3x is valid.
if 2x or -3x has that range what range does x have?

OP

Original post by TenOfThem

Exact means that it is exact ... it is the actual expansion and gives the actual value

When it is not a positive integer it is an infinite expansion and will not give an exact value

Thanks, when you say ''will not give an exact value'' what do you mean exactly? Thank you

Original post by xXxiKillxXx

Thanks, when you say ''will not give an exact value'' what do you mean exactly? Thank you

basically an exact number is any number which is rational i think

(edited 11 years ago)

OP

Original post by physics1

basically an exact number is any number which is rational i think

I know what exact number means, but we are talking about a binomial expansion which consists of several terms..

Original post by xXxiKillxXx

I know what exact number means, but we are talking about a binomial expansion which consists of several terms..

yeh and the amount of terms is finite... so exact rational answer

Original post by xXxiKillxXx

I know what exact number means, but we are talking about a binomial expansion which consists of several terms..

several (finite) terms if n is +ve integer

otherwise

infinite terms

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