# Ideas on how to easily solve this long derivation?

Mod note: Moved from a Homework section
1. Homework Statement

I want to solve:
2E, for E = exp(ikr)/r, where r = √x2+y2+z2

Thus I must solve:
d2E/dx2+d2E/dy2+d2E/dy2

The derivatives themselves are simple, but very time-consuming! Can you think of any tricks I can use to simplify the calculation?

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Samy_A
Homework Helper

## Homework Statement

I want to solve:
2E, for E = exp(ikr)/r, where r = √x2+y2+z2

Thus I must solve:
d2E/dx2+d2E/dy2+d2E/dy2

The derivatives themselves are simple, but very time-consuming! Can you think of any tricks I can use to simplify the calculation?
Since your function only depends on r, you could try a coordinate system that treats r nicely.