Let's perform the differentiation: ddx(x2·(240 -x3)) We differentiate U1 = x2 and V2 = 240 -x3 using: ddx(U1·V2) = ddx(U1)·V2 + U1·ddx(V2) Let's perform the differentiation U1: ddx(x2) 2x Let's differentiate V2: ddx(240 -x3) 0 + ddx(-x3) -13 Let's evaluate the resulting derivative (U1·V2)': 2x·(240 -x3) + x2·(-13) 2x·(240 -x3) -x23 (480x + 2x·(-x3)) -x23 480x -2x23 -x23 480x -x2 ▶Derivative: x·(480 -x)