This was one of the tricky questions included in quadratic questions pre review (I begin every A-Math lesson with pre review so that students can ’show off’ their level of understanding in the concepts we’re going to discuss. And as I guess it, everyone falls into the ‘trap’

Reasons for students falling into the ‘trap’

1. ” …. is always positive, oh b^2 – 4ac >0″
2. “ for all real values of x, so it further supports the fact that b^2 – 4ac >0″

How to avoid falling into the trap

Understand the question clearly

1. ” It is THE quadratic graph which is always positive “
2. For all real values of x is NOT equal to real roots, it just means for all values of x. (No much significance in our solution)

Structure your solution carefully

1. Draw (A picture says a thousand words)
2. Write down the 2 conclusions
3. List your a,b and c
4. Solve the inequality

2008 O level A-Math Quadratic Equations are also discussed in the video here.
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