If `y=2^(-2^((1/(1-x)))` , then find `lim_(x->1^+)y`

If x=1 then find x+y=-2 , y=?

If y=(sin^(-1)x cos^(-1)((x^2)/2))/(1+x^2) then find the value of y(1/2) + y(1/sqrt2) + y(-1/2) + y(-1/sqrt2)

y=log_e((1+x^2)/(1-x^2)) then find 225(y''-y') at x=1/2

If (x-1,y+4)=(1,2) then find x & y

If x = 1 , and x + y = -2 , then find y

If f(x+ y) = f(x) + f(y) for x, y in R and f(1) = 1, then find the value of lim_(x->0)(2^(f(tan x)-2^f(sin x)))/(x^2*f(sin x))

if x^(2)+y^(2)+(1)/(x^(2))+(1)/(y^(2))=4 then find the value of x^(2)+y^(2)

Use formula lim_(x rarr0)(a^(x)-1)/(x)=log(a) to find lim_(x rarr0)(2^(x)-1)/((1+x)^((1)/(2))-1)

If f(x)+f(y)=f((x+y)/(1-xy))x>y in R,xy!=1,lim_(x rarr0)(f(x))/(x)=2. Find f(5),f'(-2)

If (x+y): (x-y)= 4:1, then find the ratio (x^(2)+y^(2)):(x^(2)-y^(2))