The correct answer is (B): 15.937515.937515.9375
Given f(x+y)=f(x)f(y)f(x+y) = f(x)f(y)f(x+y)=f(x)f(y)
⇒f(x)=ax⇒ f(x) = ax⇒f(x)=ax (where a is constant )
Given, f(5)=4⇒a5=4⇒a=225f(5)=4 ⇒ a^5 = 4⇒ a = 2^{\frac{2}{5}}f(5)=4⇒a5=4⇒a=252
f(10)−f(−10)=a10−a−10=(225)10−(225)−10f(10)-f(-10) = a^{10}-a^{-10}=\bigg(2^{\frac{2}{5}}\bigg)^{10}-\bigg(2^{\frac{2}{5}}\bigg)^{-10}f(10)−f(−10)=a10−a−10=(252)10−(252)−10
= 24−2−4=16−116=15.93752^4-2^{-4} = 16-\frac{1}{16} = 15.937524−2−4=16−161=15.9375