Answer:
x^2+2hx+4=x
=>x^2 + 2hx +4 -x = 0
=> x^2 +hx + 4 =0
For one root, the roots have to be equal, so the discriminant = 0
b^2 - 4ac = 0
=> h^2 - 4(1)(4)=0
=> h^2 -16 = 0
=> h^2 = 16
Therefore h = 4 :)
