If 2+3i in one of the roots, then 2−3i would be other.
Since coefficients of the equation are real.
Let γ be the third root, then product of roots →αβγ=213
(2+3i)(2−3i)⋅γ=213
(4+9)⋅γ=213
⇒γ=21
The value of k will come if we put x=21 in the equation
2⋅81−49+k⋅21−13=0
⇒2k=15
⇒k=30
∴ Equation will become 2x3−9x2+30x−13=0
⇒αβ+βγ+γα=230=15
⇒(2+3i)21+(2−3i)21+(2+3i)(2−3i)=15
⇒1+2i+1−2i+13=15
⇒15=15
Hence roots exists and is equal to 21 '