Rewrite in simplest rational exponent form square root x times 4 square root x

is what I think you're saying. Converting this to exponential form, the square root becomes a 1/2.  So the square root of x is rewritten as x^(1/2).  Same with the 4 times the square root of x.  That can be rewritten as 4x^(1/2).  The rule about multiplying exponents when the bases are the same is to add the exponents, right.  So x^(1/2)*4x^(1/2) = 4x^1 or 4x