Ian Tan's answer to kristen's Secondary 4 A Maths Singapore question.

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Ian Tan
Ian Tan's answer
8 answers (A Helpful Person)
1st
Consider a quadratic equation ax^2+bx+c=0 with roots p and q

Using sum of roots and product of roots,
a=1
b=-(k+1)
c=1

For p and q to be real and distinct,
b^2-4ac > 0

Hence [-(k+1)]^2 - 4 > 0
Solving for k gives k > 1 or k < -3
kristen
Kristen
2 years ago
ahhh,, okayy thank you!
Eric Nicholas K
Eric Nicholas K
2 years ago
The current Sec 3 and Sec 4 students do not learn the chapter on “sum of roots” and “product of roots” as it has been removed from the secondary school A Maths syllabus, so you might wish to explain a little more about it.
kristen
Kristen
2 years ago
:) thank you