differentiate x*sin(x)
Let's perform the differentiation: (x·sin(x))'
For U1 = x and V2 = sin(x), use the product/quotient rule: (U1·V2)' = (U1)'·V2 + U1·(V2)'
Let's differentiate U1: (x)'
1
Let's perform the differentiation V2: (sin(x))'
cos(x)
You can evaluate the resulted derivative (U1·V2)': 1·sin(x) + x·cos(x)
sin(x) + x·cos(x)
Answer:   x·cos(x) + sin(x)