NDA2017MathematicsTrigonometric Ratios & IdentitiesActual
In PQR , R = 2 . If than ( P 2 ) and ( Q 2 ) are the roots of the equation a x^2+b x+c=0 , then which one of the following is correct?
Options
- Aa = b + c
- Bb = c + a
- Cc = a + b
- Db=c
Correct answer
C. c = a + b
Step-by-step solution
R = 2 P + Q = 2 P + Q 2 = 4 (1) ( P 2 + Q 2 )= P 2 + Q 2 1- P 2 Q 2 (2) Given, P 2 and Q 2 are roots of a x^2+b x+c=0 . P 2 + Q 2 = - b a ; P 2 Q 2 = c a . (2) ( P 2 + Q 2 )= - b a 1- c a 4 = - b a 1- c a (from (1)) 1= -b a-c -b=a-c a+b=c