Question

Find the value of k for which the equation x^2+4x+k=0 has coincident roots

Answer 1

a=1
b=4
c=k
For coincident lines,
b²-4ac=0
(4)²-4(1)(k)=0
16-4k=0
4k=16
k=16/4
k=4

Answer 2

b^2-4ac=0
a=1,b=4,c=k
16-4(1)(k)=0
16-4k=0
16=4k
k=4