We will use integration by parts twice. The integration by parts formula is:
∫udv=uv−∫vdu First, let u=x2 and dv=sinxdx. Then du=2xdx and v=−cosx. Applying integration by parts: ∫x2sinxdx=x2(−cosx)−∫(−cosx)(2x)dx=−x2cosx+2∫xcosxdx Now, we need to evaluate ∫xcosxdx. We'll use integration by parts again. Let u=x and dv=cosxdx. Then du=dx and v=sinx. Applying integration by parts: ∫xcosxdx=xsinx−∫sinxdx=xsinx−(−cosx)=xsinx+cosx Substituting this back into the original integral:
∫x2sinxdx=−x2cosx+2(xsinx+cosx)+C=−x2cosx+2xsinx+2cosx+C