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secondary 4 | A Maths
2 Answers Below
Anyone can contribute an answer, even non-tutors.
Thank u
Date Posted: 4 years ago
Views: 202
Seen, but only when I return
Actually a long division question
Any method
Not using Long division
I don’t really like Long division
Not using Long division
I don’t really like Long division
The other way is multiply all sides by 3x2 + 5 and solve the question as identity
Can you show me. Thanks
9x3 + 3x2 - 13 = (ax + b) (3x2 + 5) + cx + d
This is an identity of course. Here comparing coefficients is better.
Comparing terms in x3,
9x3 = (ax) (3x2)
a = 3
Comparing terms in x2,
3x2 = b (3x2)
b = 1
9x3 + 3x2 - 13 = (3x + 1) (3x2 + 5) + cx + d
Now here we sub in numbers.
Set x = 0
-13 = (1) (5) + 0 + d
-13 = 5 + d
d = -18
Set x = 1 (any number because only one unknown left)
9 + 3 - 13 = (4) (8) + c + d
-1 = 32 + c - 18
-1 = 14 + c
c = -15
This is an identity of course. Here comparing coefficients is better.
Comparing terms in x3,
9x3 = (ax) (3x2)
a = 3
Comparing terms in x2,
3x2 = b (3x2)
b = 1
9x3 + 3x2 - 13 = (3x + 1) (3x2 + 5) + cx + d
Now here we sub in numbers.
Set x = 0
-13 = (1) (5) + 0 + d
-13 = 5 + d
d = -18
Set x = 1 (any number because only one unknown left)
9 + 3 - 13 = (4) (8) + c + d
-1 = 32 + c - 18
-1 = 14 + c
c = -15
Will write down the full version when I return, both metbods
Alternatively m, once you find a and b, we can expand the two brackets and bring everything to one side and you will get c and d left.
See 2 Answers
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This is a partial fractions question, do remember to use long division if it fits the condition
Date Posted:
4 years ago
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I have included two different methods here, one of which is the standard long division and the other does not require long division.
Date Posted:
4 years ago
I posted a qns, can u show me using sum of root and product of root
Do you have any method same as the Long division for this qns?
The two methods in this case work. I am not sure how Long division actually works (the idea behind it), but both methods are actually related. You know how Long division works right?
I sometime Long division will miss out. So I worry
I doubt there are other methods to do those questions (at least to my knowledge). Long division is still the fastest way to get the answer, and is needed when you lean graphing techniques if you are going into jc.
Ok
You can solve it as an identity question the way I present it. After all, the denominators must be the same so you can multiply all sides by the denominator to get rid of the denominator. When you do partial fractions, we also get rid of the denominator in a similar fashion.
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