Finding electric field via potential

[DannyPhysika]

Homework Statement

The plastic rod of the length L=1 m has a non-uniform charge density λ=cx
where positive constant c =2x10^-6 [some unit]. What unit c has to have? Find the electric
potential at the point on the x-axis 1 m to the left from the left end of the rod. Find the
electric field at that point via potential. What is the direction of the field

Homework Equations

V = k integral(0 to L) dq/r

E = -dV/dx

The Attempt at a Solution

Found everything except electric field. I've tried and gotten so confused as to how to implement it. I got this so far:

dV = kλdx/(d+x)

dV/dx = kλ/(d+x)

E = -k(c)(1m)/(2m) = -8.99 x 10^3 N/C

I know it's wrong but I'm so lost as to where to fix it. Thanks

 

[DannyPhysika]

I would like to know if either:

-3.47 x 10^3 N/C

or

-1.45 x 10^4 N/C

Are correct. Thank you :)