The given function is : y= f(x) =49 [\frac{1}{7}]^x
The statements which are true regarding this function is
1. As you can observe that y is defined for all values of x , so Domain is set of all values that x can take which is set of all real numbers.
2. Also, x =\frac {\log[\frac{y}{49}]}{-\log7}, so x is defined for all values of y. Range is all values that y can take which is also set of all real numbers greater than zero, i.e y>0.
As ,x =0 then y= 49 and x_{1} =1 then y_{1} = 7,
so ,y_{1} = \frac{y}{7}.
So, Option (1),(4) and (5) are correct.