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secondary 2 | Maths
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Kkk
Kkk

secondary 2 chevron_right Maths chevron_right Singapore

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Date Posted: 3 years ago
Views: 566

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Nathaniel
Nathaniel's answer
30 answers (Tutor Details)
1st
Using the quad formula which is x=-b there line u see, complete b . Both same formula
How i get 4p-3 from 3/4
(P-3/4)(p+3) is same as (4p-3)(p+3)

And 4/9p^2 + p - 1 = 4p^2 +9p -9 (9 is multiplied)
Matthew Soon
Matthew Soon
3 years ago
The question is asking for factorization of the expression though, not solving for the variable.
Nathaniel
Nathaniel
3 years ago
But u can use that way to factorise too . I gave the factorised ans
Matthew Soon
Matthew Soon
3 years ago
Technically true, although 2 points:

1. Answer missed out the (1/9) constant

2. They may not award method marks since the question requested for factorized expressions (i.e. there's no equal sign to begin with, there shouldn't be a reason to include equations as part of the answer).

I don't disagree that the method works; it can, just not what the question was asking for?
Mr Ang
Mr Ang
3 years ago
Pardon me Mr Joel, you are helping a Sec 2 student, and Sec 2 syllabus does not cover Quadratic Formula. Therefore, your method would not be acceptable.

Second point - your factorised form, when expanded, will not give the original expression as what Mr Soon had mentioned. Kindly take note eh, thanks.
(a) Factorize by (1/9) first so your constants are whole

(1/9)(4p^2 + 9p - 9)
= (1/9)(4p-3)(p+3)


(b) Factorize step by step. Start with (1/5) first to make all the constants whole; then factorize common terms (in this case, its r), then factorize the quadratic expression of q terms.

(1/5)(3r - 4qr - 64q^2r)
= (r/5)(3 - 4q - 64q^2)
= (r/5)(-16q+3)(4q+1)
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Matthew Soon
Matthew Soon's answer
94 answers (Tutor Details)
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WT Cheng
Wt Cheng's answer
97 answers (Tutor Details)
Hi, answers as shown above.
Mr Ang
Mr Ang
3 years ago
Pardon me Mr Cheng, do note that for general expressions, you shouldn't multiply a constant to get rid of the fractions (unless they were equations).

If you expand both your answers, they will not give the original expressions . Kindly take note eh, thanks.
WT Cheng
WT Cheng
3 years ago
Well noted Mr Ang. I will take note of this. Appreciate your kind advice.