jnu 2011

[seema]

If p and q are the roots of the equation x^2-bx+c=0, then what is the equation if the roots are (pq+p+q) and (pq-p-q) ?

a) x^2-2cx+(c^2-b^2)=0
b) x^2-2bx+(c^2+b^2)=0
c) bcx^2-2(b+c)x+c^2=0
d) x^2+2bx-(c^2-b^2)=0

[s]

in x^2-bx+c=0 sum of roots p+q=b, product of roots pq=c

sum of roots (pq+p+q) and (pq-p-q) is 2pq or 2c
product of roots (pq+p+q)(pq-p-q)=(pq)^2-(p+q)^2 or c^2-b^2

in a quadratic equation;

x^2-(sum of roots of equation)x+(product of roots)=0
=> x^2-2cx+c^2-b^2=0...is the quadratic eqn

[seema]

thanks a lot.. :)