RRB Technician 2014 Ques 15
Question: If one root of $ x^{2}-4x-K=0 $ is 6, then the value of K is
Options:
A) 16
B) 9
C) 5
D) 12
Show Answer
Answer:
Correct Answer: D
Solution:
- One root of the equation $ x^{2}-4x-K=0 $ is 6. Let other root $ =\beta $ $ \alpha +\beta =-\frac{b}{a}=\frac{4}{1}=6+\beta =4 $
$ \Rightarrow $ $ \beta =-2\Rightarrow \alpha \times \beta =\frac{c}{a}=\frac{-K}{1} $
$ \Rightarrow $ $ 6x-2=-K\Rightarrow K=12 $
BETA
