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:Help...........for how many positive integers n is n^3 -8n^2+20n-13 a prime number??

Mathematics
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factorize it
how watever i get is not a prime number
why?

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Other answers:

oh
but then ii have to plug in millions of values
what u want to calculate
(n^3 -8n^2+20n-13) a prime number
or n is a prime number
for n i will have to put millions of values to find how may n positive integers satisfy n^3 -8n^2+20n-13 to be a prime number
ok
so,what to do??
anything i can do to narrow down the possobilities
no answer given....
ok see for 2 it is prime number
wait i took wrong concept
\[(x-1) \times [(x-7)x + 13]\]
where x is n
ok
now see the first term is (x-1). and other than 2 no other even number is a prime number right
i got the answer
no n does not have to be a prime number n^3 -8n^2+20n-13 has to be a prime number
yeah i know (x−1)×[(x−7)x+13] it has to be prime
yup so x can be anything greater or equal to 2
first term is (x-1) and two is the only even prime number.
but if u will subtract 1 from any other prime number the resultant will be divisible by 2
getting my point or not
x can be 4
yeah u r right
it means that for any odd integer other than 3 u will not get a prime number
yeah
Superb sheggy!
also the number cannot be graeter than 7
oh yeah
thanks fool bhai
so u are having a limited space to work out that is from 1 to 7
yes sheg u got it so answer is n=2,3,4
no actually 2 to 7
hahahaa right 2 to 7
but for 7 it will be 0
wait why cant it be greater than 7?
try any number u will get the answer
odd numbers cannot be included ok thats true
as i had told u any odd number subtracted by one will result in even number so it will be divisible by 2.........do u accept it or not
is 323 a prime number?
yeah i acept
its not div by 17
323 is divisible by 17
so 323 is not a prime number
4387 ?
what u have put x = ??
n=20
1443?
gtg shall come bak in 15 min
for n = 20 it should be equal to 5187
oh yeah 1443?
no
20^3 - 8*20^2 + 20*20 -13 =8000 - 3200 + 400 -13 = 8400 - 3213 = 5187
gtg cum bak in 15 mins
dear i had told u for no value greater than 7 it would fit
and both 1443 and 5187 is divisible by 3
i am bak so what to do now?
for no value greater than 7 that too even number it will not be a prime number
http://www.wolframalpha.com/input/?i=x^3-8x^2%2B20x-13+where+x+%3D+20 visit this website and plug in different value of x u will get the answer
king u there

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