can someone confirm if i am doing this correctly

5xcos(4x) solve using integration by parts

let V=5x so dv/dx=5

du/dx=cos(4x) u=1/4sin4x

5x(1/4sin4x)-int 5(1/4sin4x)

(5x/4)sin4x + (5/16)cos4x

if i am going wrong somewhere can you please explain thanks.