given this equation: f(x,y) = (xysin(x-y)) / (1+(x^2)+(y^2)) , for (1,1,0) i need to compute the partial derivatives and graph the surface and the tangent plane at the given point. this is as far as i got before getting stuck > f := xysin(x-y)/(1+x^2+y^2); xysin(x - y) ------------ 2 2 1 + x + y > plot3d(f, x = -3 .. 3, y = -3 .. 3, grid = [2, 2]);

i am supposed to solve this differential equation: y(prime) = 2(1+t)*y^3 where y(o) = 2^(-1/2) this is what ive done so far: > with(PDEtools, declare): with(DEtools): > declare(y(t)=t, prime=t): > diff(y(t),t)= 2(1+t)*(y^(3)); y(0)=2^(-1/2); the problem is that the (1+t) part always drops. what am i doing wrong?