Question 873146
{{{ z= sqrt( z^2 + 4z - 18 ) }}}



{{{ z^2= (sqrt( z^2 + 4z - 18 ))^2 }}} Square both sides (to undo the square root on the right side)



{{{ z^2= z^2 + 4z - 18 }}}



{{{ z^2-z^2 = 4z - 18 }}}



{{{ 0 = 4z - 18 }}}



{{{ 4z - 18 = 0 }}}



{{{ 4z = 18 }}}



{{{ z = 18/4 }}}



{{{ z = 9/2 }}}



I'll let you check the answer.