limx→0ax+xcosxbsinx⇒limx→0x(a+cosx)bsinx
⇒ on using Hospital rule, we get
⇒limx→0ddx[(a+cosx)]ddx[bsinx]=limx→0a+cosx−xsinxbcosx
again using L Hospital rule we get
⇒limx→0−sinx−sinx−xcosx−bsinx
again using L'Hospital rule
limx→0−2cosx−cosx+xsinx−bcosx
⇒limx→0−3cosx+xsinx−bcosx
⇒limx→0+3b−xtanxb
using limit we get
⇒3b to = 3b