if 2f(xy)={f(x)}^y+{f(y)}^x x,y belong to R and f(1)=2 . Find summation100 r-1 f(r)=? Share with your friends Share 0 Neha Sethi answered this Dear student We have2fxy=fxy+fyx and f1=2If fxy=fx+fyThen fx=logaxIf fxy=fx-fyThen fx=logaxIf fx+f1x=fx.f1xThen fx=1±xnIf fxy+fyx=2fxyThen fx=ax for any number a Given : 2fxy=fxy+fyx Put x=1 and y=x we get2fx=f1x+fx 2fx-fx=f1xgiven f1=2⇒fx=2xSo, fr=2rSo, ∑r=1100fr=∑r=1100 2r Regards -1 View Full Answer