The electric potential in a region of space is / [V=350//sqrt{x ^{2}+y ^{2}}/] where x and y are in meters. what is the strength of electric field at (x, y) = (2.6,2.8) m?

So the given value or the formula in getting the electric potential region of space is V=350/sqrt of x^2+y^2. So the given data is x and y is equals to 2.6 and 2.8. So in my calculation i came up with an answer of 91.6