X-component of electric field from charge Q1 at point P

[brioches]

Homework Statement

A positive charge of magnitude Q1 = 8.5 nC is located at the origin. A negative charge Q2 = -8.5 nC is located on the positive x-axis at x = 16.5 cm from the origin. The point P is located y = 7.5 cm above charge Q2. Calculate the x-component of the electric field at point P due to charge Q1. Write your answer in units of N/C.

Homework Equations

E_field = (K)(Q)/(r²)

The Attempt at a Solution

I found the E-field created by Q1 by doing (k)(Q1)/(r²). I found r to be .18125 by performing the Pythagorean Theorem on the x and y legs. I then multiplied this answer by x/r because it asks for just the x-component, which is the E-field times cos(θ), and cos(θ) is adjacent/hypotenuse. I got 421.506 for the E-field and .910345 for cos(θ), and after multiplying these, I got 383.716, which is not the right answer. Any help is much appreciated.

 

[haruspex]

I got 421.506

You seem to have used kq/r, not kq/r².

 

[brioches]

You seem to have used kq/r, not kq/r².

Welp, that was definitely it. Thanks so much!