Respuesta :

elhamrah11
Distribute 9z to 7z and -4 
You get 56z^2 - 36z = 6 
56^2 - 36 - 6 = 0 
Solve using quadratic formula 
z is approx 0.78 and approx. -0.14
Expand 9z(7z - 4): 63z^2 - 36z
63z^2 - 36z = 6
Subtract 6 from both sides
63z^2 - 36z - 6 = 6 - 6
Simplify
63z^2 - 36z - 6 = 0
z= 6 + radicant 78/ 21, z= 6- radicant 78/ 21