Danny Low's answer to Isaac's Secondary 2 Maths Singapore question.
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Hope this helps
Date Posted:
1 year ago
Why is it that we start from ay, then suddenly it becomes 3ay
If we had taken 3ay at the start we would not have a perfect square to apply the a2 - b2 = (a+b)(a-b) formula. 225 is a square but 75 is not, that’s why the pulling out of 3 can only be done later
I just realised I could have pulled out 9ay at step 1, that would have made it less confusing although at the end the answer is the same. sorry about that, hope this helps
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