show that

limit x tends to (-infinity) (e^x - e^-x)/(e^x + e^-x) = -1

f(x)= (e^x-1/e^x)/(e^x+1/e^x)

     =  (e^2x-1)/(e^2x+1)

and now simply put the value of .

see that x is negative so e^2x will become 1/e^2x(number)    here the value of x or number is infinity so will gaive infinite value at denominator . 1 diveded by by infinity is almost zero.

so limit becomes -1/1=  -1

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