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secondary 3 | A Maths
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Rella
Rella

secondary 3 chevron_right A Maths chevron_right Singapore

Can you help me with this q. Thx

Date Posted: 4 years ago
Views: 341

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Eric Nicholas K
Eric Nicholas K's answer
5997 answers (Tutor Details)
1st
Logical reasoning is needed at the last part.
Rella
Rella
4 years ago
So what is the final answer
Eric Nicholas K
Eric Nicholas K
4 years ago
We need to show that b2 - 4ac > 0 in this question.

It’s a ‘show that’ question.

Once you obtain b2 - 4ac = q (5q - 4), you need to explain why that product is positive when q is negative. Once you have done so, you can conclude by saying that b2 - 4ac > 0 when q is negative, and this translates to having two real and distinct roots.
Eric Nicholas K
Eric Nicholas K
4 years ago
As a side note, in ‘show that’ questions such as this one, we cannot start by immediately saying that b2 - 4ac > 0; in other words, you must not write the ‘> 0’ while attempting to prove that it is indeed > 0.
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Tong Woei Horng
Tong Woei Horng's answer
385 answers (Tutor Details)