Answer:
[tex]z = -3[/tex]
Step-by-step explanation:
Given
[tex]z^2 +11z+9 = 5z[/tex] --- the correct equation
Required
Solve
Equate to 0
[tex]z^2 +11z-5z+9 = 0[/tex]
[tex]z^2 +6z+9 = 0[/tex]
Expand
[tex]z^2 +3z+3z+9 = 0[/tex]
Factorize
[tex]z(z +3)+3(z+3) = 0[/tex]
Factor out z + 3
[tex](z +3)(z+3) = 0[/tex]
Split
[tex]z + 3 =0[/tex] --- twice
[tex]z = -3[/tex]
