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secondary 2 | Maths
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hyeongjun best boy
Hyeongjun Best Boy

secondary 2 chevron_right Maths chevron_right Singapore

for b)i), why do i let m be 10

Date Posted: 3 years ago
Views: 246

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when you let m=10, the expression will be 4(100) + 7(10) + 3, which is equal to 473. so when you substitute m=10, your factorisation in part (a) will be equal to the factors for 473.
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Chua Yong Qi
Chua Yong Qi's answer
22 answers (Tutor Details)
1st
hyeongjun best boy
Hyeongjun Best Boy
3 years ago
why sub 10 and not other numbers
Chua Yong Qi
Chua Yong Qi
3 years ago
subbing other numbers will not give you 473, which is what you are trying to factorise
ZQ Chan
ZQ Chan
3 years ago
your answer in (a), if I am not wrong, should be
(4m + 3 ) (m + 1). As original commenter said, you will need this to answer your b(i).

to find the factors of 473, you will expect your 2 factors to multiply one another to obtain 473. and the part a is trying to help you here.
(4m + 3) (m + 1) = 473.
Basically your 2 factors being 4m + 3 and m + 1. (might be hard to digest but think about it)

hence,
(4m + 3) (m + 1) = 473
aka 4m2 + 7m + 3 = 473.
you will need an m that will make the LHS of that equation equal to 473.

The question is already making it very very obvious m has to be 10. You will definitely need 4(100) + 7(10) + 3 to get 473. hence M being 10.

Now that we know M is 10,
your 2 factors are 4m + 3 and m + 1. Sub 10 in.

And Nothing of what I just said is fundamentally different from what original commenter said. Just a more detailed breakdown.
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Teo Jer Rei
Teo Jer Rei's answer
12 answers (A Helpful Person)
We let m=10, because that way, we can convert 473 into the quadratic equation we found in (a), which we can then simplify and find the factors

Hope this helps!