7 – 4x –x2 = 0

(i) 7 – 4x –x² = 0

Sol. 7 – 4x – x² = 0

∴  – x² – 4x + 7 = 0

Multiplying throughout by –1, we get,

x² + 4x – 7 = 0

Now it is in the standard form of ax² + bx + c = 0