Only one value has been provided, so let x2=ln(4) as an illustration of the method.
y1=e0.5x₁ and y2=e0.5x₂, so y1=1 (because x1=0) and y2=e0.5ln(4)=eln(√4)=2.
(y-y1)/(x-x1)=(y2-y1)/(x2-x1),
(y-1)/x=(2-1)/ln(4), y-1=x/ln(4), y=x/ln(4)+1 is the linear interpolation.
y=0.7213x+1 is the approximate linear interpolation.