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secondary 4 | E Maths
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Meredy
Meredy

secondary 4 chevron_right E Maths chevron_right Singapore

Can i present my answer as 2b-5A/A+b instead of 5A-2b/b+A

Date Posted: 3 years ago
Views: 191
AHMAD JABBAR BIN ABDUL HALIM
AHMAD JABBAR BIN ABDUL HALIM
3 years ago
cannot. its not the same
Tung Jing Hao Ryan
Tung Jing Hao Ryan
3 years ago
Nope it’s not the same. 5A has to be positive and 2b has to be negative
J
J
3 years ago
c = (5b - 2A)/(b + A)

Or

c = (5b - 2A)/(A + b)

For the denominator, a + b = b + a so the order does not matter.


BUT, for the numerator, 5b - 2A and 2A - 5b are the negatives of each other. They aren't the same.

Something similar would be like :
5 - 2 = 3 but 2 - 5 = -3, which ≠ 3


If you want to express the numerator as 2b - 5A, you have to change your denominator to the negative as well.


c = (5b - 2A)/(b + A)

= -(5b - 2A)/-(b + A)

= (-5b + 2A)/(-b - A)

= (2A - 5b)/(-b - A)

(You can skip the middle two steps, just showing for clarity.)

This is similar to :

c = 5/2 = -5/-2



But typically, we try to leave the expression with as few negative signs as possible, so the first two on top are preferred.

See 1 Answer

Hi Meredy,

No. Because you are expressing c in terms of the other terms.

When you multiply the RHS with -ve,
you also need to multiply the LHS with -ve, which will give you: minus c
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WT Cheng
Wt Cheng's answer
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