It is known that the domain of function y = f (x) is R +, f (8) = 3. For any x ∈ R, f (x1x2) = f (x1) + F (x2) conjecture expression Reasonable reasoning content, .' | | / | |/-.( | |\_ ._ \ | | \ \`;| | > |/| | / // | | |// | | \(\ | | `` | | | | | | | | | \\ _ _ \\| \// |//_ _ \// _ ^ `^`^ ^`` `^ ^` ``^^` `^^` `^ `^

It is known that the domain of function y = f (x) is R +, f (8) = 3. For any x ∈ R, f (x1x2) = f (x1) + F (x2) conjecture expression Reasonable reasoning content, .' | | / | |/-.( | |\_ ._ \ | | \ \`;| | > |/| | / // | | |// | | \(\ | | `` | | | | | | | | | \\ _ _ \\| \// |//_ _ \// _ ^ `^`^ ^`` `^ ^` ``^^` `^^` `^ `^

The general function satisfying the form of F (x1x2) = f (x1) + F (x2) is logarithmic function
F (x) = loga (x), the domain of definition is r+
And f (x1) + F (x2) = loga (x1) + loga (x2) = loga (x1x2) = f (x1x2)
And f (8) = loga (8) = 3
∴a=2
∴f(x)=log2(x),x＞0