i got only one answer....f(x)=1
strange.....
dif the equation wrt x keeping y const.....
yf'(xy)=f'(x)f(y)-f'(x+y)+1
now onc putting y=0
and onc x=0,y=x
find all functions f:Q→R such that for all x,y ξ Q
f(xy)=f(x)f(y)-f(x+y)+1
x,y ξ Q means for all x,y belonging to Q.
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3 Answers
sidsgr88 Bora
·2009-02-15 08:03:12