Chapter 10 - Radical Expressions and Equations - 10-4 Solving Radical Equations - Practice and Problem-Solving Exercises - Page 623: 9

$z=36$

$Given,$ $\sqrt z-1=5$ $\sqrt z-1+1=5+1$ $\sqrt z=6$ Squaring,we get: $z=36$ We need to check by putting the obtained value in the original equation : $L.H.S = \sqrt 36 - 1=6-1=5=R.H.S$ Hence, $z=36$ is a valid solution