If z is not equal to zero, and z=6zs−9s2−−−−−−−−√z=6zs−9s2, then z equals:  Choose the correct choice from the following options:	A) s	B) 3 s	C) 4 s	D) - 3 s	E) - 4 s

Rationale: squaring on both the sides gives z ^ 2 = 6 zs - 9 s ^ 2 = z ^ 2 - 6 zs + 9 s ^ 2 = z ( z - 3 s ) - 3 s ( z - 3 s ) = ( z - 3 s ) ( z - 3 s ) = z = 3 s answer = b
Answer: B