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.