Question

How do you factor the expression `9x^2 + 12x + 4`?

Answer 1

Use the quadratic rule.

Explanation:

You first need to calculate `b^2 - 4ac`. Here, `b^2 - 4ac = 12^2- 4*9*4 = 0`. So it only has one root, given by the quadratic rule : `-12/18 = -2/3`.

So the expression `9x^2 + 12x + 4` can be factorised as `9(x + 2/3)^2`.