Complex Numbers And Quadratic Equations question 792
Question: For what value of k will the equation $ x^{2}-(3k-1)x+ $ $ 2k^{2}+2k $ have equal roots [Karnataka CET 1998]
Options:
A) 5
B) 9
C) Both (a) and (b)
D) 0
Show Answer
Answer:
Correct Answer: C
Solution:
For the equation to be real roots, $ b^{2}-4ac=0 $
Þ $ {{(3k-1)}^{2}}=4(2k^{2}+2k-11) $
Þ $ 9k^{2}+1-6k=8k^{2}+8k-44 $
Þ $ k^{2}-14k+45=0 $
Þ $ (k-5)(k-9) $ = 0 $ k=5 $ or $ k=9 $ .
BETA
