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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[...] missed out this workshop, I’ll be sharing in the next few posts some of the fatal mistakes (Quadratic Equations, Logarithms) you must NEVER make! Let’s get the house rules right on day 1 before we begin [...]