# Binomial expansion quick Qs.Watch

#1
Is there a way to check the accuracy of your expansion of a binomial expression with a negative or a fractional power?
0
4 years ago
#2
(Original post by zee600)
Is there a way to check the accuracy of your expansion of a binomial expression with a negative or a fractional power?
Substitute x = 0.01 and evaluate the first few terms and compare it to the value of the expression you are expanding?
0
#3
Umm...I fear not..
Thats for finding approximation of a particular constant through the binomial expansion not the accuracy of the binomial itself
(U can check if the expansion is right only if the question has a subdivision where it asks you to find the approximation of a particular constant since it would give u the right answer...
2nd) you cant substitute x=0.01 in every expression
0
4 years ago
#4
(Original post by zee600)
Umm...I fear not..
Thats for finding approximation of a particular constant through the binomial expansion not the accuracy of the binomial itself
(U can check if the expansion is right only if the question has a subdivision where it asks you to find the approximation of a particular constant since it would give u the right answer...
2nd) you cant substitute x=0.01 in every expression
Can you expand on what exactly it is that you want to test, i.e. give an example of a series and the value you're trying to estimate?
0
#5
(Original post by davros)
Can you expand on what exactly it is that you want to test, i.e. give an example of a series and the value you're trying to estimate?
Q) Expand the following binomial expression: (8-3x)^1/3

I have expanded this or any other expression of a similar type, how, in an exam do I ensure that the coefficients I have calculated are accurate?

Since expanding takes time and for me even If it looks good the answer turns out to be wrong at times: just wish to prevent that!
0
4 years ago
#6
(Original post by zee600)
Q) Expand the following binomial expression: (8-3x)^1/3

I have expanded this or any other expression of a similar type, how, in an exam do I ensure that the coefficients I have calculated are accurate?

Since expanding takes time and for me even If it looks good the answer turns out to be wrong at times: just wish to prevent that!
Oh right, so when you said "accuracy of expansion" you basically meant "how do I make sure my coefficients are correct?".

In general there's no quick way (unless you're dealing with positive integer exponent when you can just multiply out the brackets long-hand).

Just be careful and methodical in your working and lay things out neatly so you can re-read it easily when you come to check at the end of the exam. If you have time, of course, you can repeat the process and make sure you get the same answer as originally.
0
#7
Iwas hoping there d be a way...
0
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