Thread: [SOLVED] vector identity proof

Need help proving this
let f(x,y,z) and g(x,y,z) be any C^2 scaler functions. Without using the basic identities of vector analysis prove that

grad.(fgradg-ggradf)=fgrad^2g- ggrad^2f

(ive put grad instead of the upside down triangle symbol)

thanks

Originally Posted by sam1986

Need help proving this
let f(x,y,z) and g(x,y,z) be any C^2 scaler functions. Without using the basic identities of vector analysis prove that

grad.(fgradg-ggradf)=fgrad^2g- ggrad^2f

(ive put grad instead of the upside down triangle symbol)

thanks

To start you off:



Now apply the product rule to the what is inside the right most summation
and simplify and you should have what you want.

RonL