If `f (x)=4x -x ^(2),` then `f (a+1) -f (a-1) =`

If f(x)=4x-x^2 then find f(a+1)-f(a-1)

If f(x)=x^(2) , then evaluate : (f(x+1)-f(x-1))/(4x)

If f(x)=x^(2) , then evaluate : (f(x+1)-f(x-1))/(4x)

If f(x)=(4+x)/(4-x) , then find f(2^(-1)) .

If f(x)=log((1+x)/(1-x)), then (a) f(x_(1))f(x)=f(x_(1)+x_(2))(b)f(x+2)-2f(x+1)+f(x)=0 (c) f(x)+f(x+1)=f(x^(2)+x)(d)f(x_(1))+f(x_(2))=f((x_(1)+x_(2))/(1+x_(1)x_(2)))

{:(1.if F (X) = (1)/(x) then f'(1) =A, 2.If f (x) = (x+1)/(x+3) then f '(-1) =B),(3.If f(x)=x^(2)then f'(1)=C,4. If f(x)=logx then f'(3)=D):} The ascending order of A,B,C ,D is

If f(x)=cos(log x), then value of f(x)f(4)-(1)/(2){f((x)/(4))+f(4x)} is (a) 1(b)-1(c)0(d)+-1