Complex Numbers And Quadratic Equations question 539
Question: If the difference of the roots of $ x^{2}-px+8=0 $ be 2, then the value of p is [Roorkee 1992]
Options:
A) $ \pm 2 $
B) $ \pm 4 $
C) $ \pm 6 $
D) $ \pm 8 $
Show Answer
Answer:
Correct Answer: C
Solution:
As given, if $ \alpha ,\beta $ are the roots, then $ \alpha +\beta =p $ and $ \alpha \beta =8 $
$ \therefore {{(\alpha +\beta )}^{2}}-{{(\alpha -\beta )}^{2}}=4\alpha \beta $
Þ $ p^{2}-2^{2}=4(8)\Rightarrow p^{2}=36\Rightarrow p=\pm 6 $
BETA
