Question

if one root of quadratic equation 2x^2+kx+1=0is2.find the value of k?

Answer 1

2(2)²+2k+1=0
8+1+2k=0
9= -2k
k= -9/2

Answer 2

let the 2nd root be p
As we know that sum of the roots
2+p=-k/2....(1)

product of the roots
2p=1/2
p=1/4
put the value of p in (1)
2+1/4=-k/2
9/4=-k/2
k=-9/2