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secondary 2 | Maths
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How to do this and also a brief explanation... ty
Date Posted: 4 years ago
Views: 200
to solve this directly you need to do completing the square as explained in the answer that Eugene has posted. however completing the square is normally taught in sec 3, so in case you have not learnt completing the square, here is another possible way …
(x+a)2 + b
= x2 + 2ax + a2 + b
= x2 - 5x - 7
comparing terms,
2a = -5 gives a = -5/2
a2 + b = -7
(-5/2)2 + b = -7
gives b = -53/4
therefore
x2 - 5x - 7 = (x -5/2)2 - 53/4
(x+a)2 + b
= x2 + 2ax + a2 + b
= x2 - 5x - 7
comparing terms,
2a = -5 gives a = -5/2
a2 + b = -7
(-5/2)2 + b = -7
gives b = -53/4
therefore
x2 - 5x - 7 = (x -5/2)2 - 53/4
See 1 Answer
done
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clear
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I hope this helps.... The one written in black pen is if you understand completing the square well then you can just do that because that’s what I always do hahaha. The one in blue pen is the actual working.
Date Posted:
4 years ago
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