1this was an objective problem from last year's AITS series
A quadratic equation with integral coefficients has two prime numbers as its roots.
If the sum of the coefficients of the equation is prime then the sum of the roots is - ?
Post the method also
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7 Answers
62let the quadratic be
p and q be the roots...
a(x-p)(x-q)=0
a has to be + or -1 else it will be divisible by
sum of coeff = a(1-p)(1-q)
we can eliminate -1 case separately..
(1-p) has to be 1 .... or (1-q) has to be :)
also (1-q) to be prime needs 2 as the only possible value.. cos all other primes -1 is an even number which is greater than 2!
1ya i followed the same method ...
one of my friends gave amethod involving cases ..
i wanted to see what you adopt to bhaiyya.
62may be i used the wrong phrase.. you could say deal that case separately...
It is basically similar.. if not the same!