z – 7/z = 4z + 5


(viii) z – 7/z = 4z + 5

Sol. z – 7/z = 4z + 5
Multiplying throughout by z, we get,
z2 – 7 = 4z2 + 5z
 z2 – 4z2 – 5z – 7 = 0
∴  –3z2 – 5z – 7 = 0
Changing the Sign,
∴ 3z2 + 5z + 7 = 0
Here a = 3, b = 5, c = 7 are real numbers
where a ≠ 0

So it is a quadratic equation in variable z.