Write 343 with an exponent by using 7 as the base

Just tell me how to set up the equation.

Find the domain of the following expression: 1/(√x)-2

Which equation shows the variable terms isolated on one side and the constant terms isolated on the other side for the equation -1/2x+3=4-1/4x? a. -1/4x=1 b. -3/4x=1 c. 7=1/4x d. 7=3/4x