4x2 – 12x + 5
We have,
4x2 – 12x + 5 = 4 (x2 – 3x + \(\frac{5}{4}\))
= 4 [x2 – 3x + (\(\frac{3}{2}\))2 – (\(\frac{3}{2}\))2 + \(\frac{5}{4}\))] [Therefore, adding and subtracting (\(\frac{3}{2}\))2]
= 4 [(x - \(\frac{3}{2}\))2 – 12] (Therefore, completing the square)