D[(x^2) Sin[x + y], x]

example1 = D[(x^2) Sin[x + y], x]

example1 /. {x -> (π/4), y -> (π/6)}

example2 = D[(x^2) Sin[x + y], {x, 2}, {y, 3}]

example2 /. {x -> (π/4), y -> (π/6)}