<p>Hey,</p>
<p>I've got this function:</p>
<p>f(x) = (x + y)(x^2 + y^2)</p>
<p> </p>
<p>By applying the product rule by hand I get the following partial derivative (with respect to x):</p>
<p>df/dx = (x^2 + y^2) + (x + y)2x</p>
<p> </p>
<p>I would expect Maple to give me the same result but instead I get the following:</p>
<p>f := (x + y)(x^2 + y^2)</p>
<p>diff(f,x) = 2*(D(x))(x^2 + y^2)*x + 2*(D(y))(x^2 + y^2)*x</p>
<p> </p>
<p>This has me a bit stumped so I'm hoping someone is able to help me out.</p>
<p>Thanks in advance.</p>