Mathematica is fussier than Wolfram Alpha about its input syntax. Try
NIntegrate[Sqrt[1 + (.00035 x^2)^2], {x, -625, 625}]
Domanda
Here's my input:
NIntegrate[sqrt[1 + (.00035 x^2)^2], {x, -625, 625}]
The result is:
NIntegrate::inumr: "The integrand sqrt[1+1.225*10^-7\ x^4] has evaluated to non-numerical values for all sampling points in the region with boundaries {{-625,0}}."
This links me to a page where I basically am told that I have to define x. Isn't that exactly what the range given as a second argument is doing? What am I not doing here?
I can put the exact same syntax into WolframAlpha and get the right answer:
Soluzione
Mathematica is fussier than Wolfram Alpha about its input syntax. Try
NIntegrate[Sqrt[1 + (.00035 x^2)^2], {x, -625, 625}]