Find out the value of k for which the expression x2+(k+5)x−k−5=0 has two distinct real roots.
Soln:
For the equation given D=(k+5)2+4(1)(k+5)=k2+10k+25+4k+20=k2+14k+45
For the equation to have two distinct roots: D>0
k2+14k+45>0 (k+9)(k+5)>0
Value of k will be (−∞,−9)∪(−5,∞)
Hence option (b)