Respuesta :

subsitute 7 for x

√(2k²+17)-7=0
add 7 to both sides
√(2k²+17)=7
squaer both sides
2k²+17=49
minus 17 both sides
2k²=32
divide both sides by 2
k²=16
square both sides
k=+/-4

we are given that k>0 so k=4


answer is C