If 8f(x)+6f1x=x+5 and y=x2f(x) , then dydx at x=−1 is equal to
112
114
1914
−114
given 8f(x)+6f1x=x+5.........(1) ×8 Put x=1x⇒8f1x+6f(x)=1x+5.......(2) ×6solving 1 and 2 From (1)&(2) f(x)=1288x−6x+10y=x2f(x)⇒y=1288x3−6x+10x2dydx=12824x2-6+20xdydxx=−1=−114