See Eric Nicholas K's answer to Elle's Junior College 1 H2 Maths Singapore question

Eric Nicholas K's answer to Elle's Junior College 1 H2 Maths Singapore question.

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An idea, but you have to be mathematically prepared to deal with the problematic algebraic expressions.

Date Posted: 4 years ago

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Elle

4 years ago

Thank you!!

4 years ago

To show mathematically why y > 0 for the last part : (in addition to a qualitative reasoning)

y/x = 3 √(2a - 1)/(2a + 1)

Since a > ½, 2a > 1

2a + 1 > 2 > 0 and 2a - 1 > 0

So (2a - 1)/(2a + 1) > 0

And hence 3√(2a - 1)/(2a + 1) > 0