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'
- " .... is always positive, oh b^2 - 4ac >0"
- " 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
- " It is THE quadratic graph which is always positive "
- 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
- Draw (A picture says a thousand words)
- Write down the 2 conclusions
- List your a,b and c
- Solve the inequality
2008 O level A-Math Quadratic Equations are also discussed in the video here.
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