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f(x)=2x^2−146x+c has 2 roots that are positive prime numbers. What is c?
 one year ago
 one year ago
f(x)=2x^2−146x+c has 2 roots that are positive prime numbers. What is c?
 one year ago
 one year ago

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arun8408Best ResponseYou've already chosen the best response.0
or roots to be positive D>0 i.e. b^2  4ac >0 D=b^2  4ac = (146)^2  (4*2*c)>0 =>21316  8c>0 =>8c<21316 => c<5329/2 is dis the ans??
 one year ago

ParthKohliBest ResponseYou've already chosen the best response.4
use the sum of roots and product of roots formulae.
 one year ago

ParthKohliBest ResponseYou've already chosen the best response.4
\[\dfrac{146}{2} = \alpha + \beta\]and\[\dfrac{c}{a} = \alpha \beta\]where \(\alpha\), \(\beta\) are the required prime roots.
 one year ago

ParthKohliBest ResponseYou've already chosen the best response.4
Know any two prime numbers with sum \(73\)?
 one year ago

ParthKohliBest ResponseYou've already chosen the best response.4
I meant\[\dfrac{(146)}{2} = \alpha + \beta\]
 one year ago

arun8408Best ResponseYou've already chosen the best response.0
but 2 prime number tat makes 73??
 one year ago

ParthKohliBest ResponseYou've already chosen the best response.4
Yeah, do you know any two such prime numbers with sum 73?
 one year ago

klimenkovBest ResponseYou've already chosen the best response.2
If one of this primes is odd, the second must be even, because \(\alpha +\beta=73\). But how many even primes do you know?
 one year ago

AzteckBest ResponseYou've already chosen the best response.0
Start from the very first prime number and work your way through. That's a hint for you.
 one year ago

ParthKohliBest ResponseYou've already chosen the best response.4
There is only one even prime number.
 one year ago

AzteckBest ResponseYou've already chosen the best response.0
I stress on the word "first" in that statement.
 one year ago

ParthKohliBest ResponseYou've already chosen the best response.4
And of course, when you subtract the even prime, you will get another prime.
 one year ago

klimenkovBest ResponseYou've already chosen the best response.2
@ParthKohli 17  prime. 2  even prime. If I subtract 17  2 = 15  I will get not prime.
 one year ago

ParthKohliBest ResponseYou've already chosen the best response.4
No, in this case you must!
 one year ago

saloniiigupta95Best ResponseYou've already chosen the best response.0
This case is NOT having such a situation though :)
 one year ago

ParthKohliBest ResponseYou've already chosen the best response.4
This question would have no answer if you would not get another prime number after subtracting 2.
 one year ago

klimenkovBest ResponseYou've already chosen the best response.2
Nobody guarantees you that this must have an answer.
 one year ago

saloniiigupta95Best ResponseYou've already chosen the best response.0
Hey this is a problem of the present week's Brilliant Challenges... Shouldn't be discussed here actually... Between, Awesome site for maths lovers... https://brilliant.org/
 one year ago
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