IM's answer to Nicky's Secondary 3 A Maths Singapore question.
done
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Hope this helps!
Date Posted:
3 years ago
Omg yes thank you!!! I was thinking how part (i) was linked to part (ii) and you answered it!
Part i is not supposed to be done that way in A Maths. The expression should not be expanded right from the start. You are likely to be deducted marks for it.
Nic, follow this formula
a3 - b3
= (a - b) (a2 + ab + b2)
(x + 3)^3 - x^3
= (x + 3 - x) [(x + 3)^2 + (x + 3)(x) + x^2]
= 3 (x2 + 6x + 9 + x2 + 3x + x2)
= 3 (3x2 + 9x + 9)
= 9 (x2 + 3x + 3)
Nic, follow this formula
a3 - b3
= (a - b) (a2 + ab + b2)
(x + 3)^3 - x^3
= (x + 3 - x) [(x + 3)^2 + (x + 3)(x) + x^2]
= 3 (x2 + 6x + 9 + x2 + 3x + x2)
= 3 (3x2 + 9x + 9)
= 9 (x2 + 3x + 3)
Hi Eric! I actually did part (i) on my own already before I asked this question. I just needed help
With part (ii). But yes my working is exactly the same as the one you typed out! Thankss
With part (ii). But yes my working is exactly the same as the one you typed out! Thankss
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