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#1 2008-04-12 00:24:06
- glenn101
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- Registered: 2008-04-02
- Posts: 108
Polynomial Identities
ok this question just confuses me so much, I don't know where to begin. Ok here is the question.
If(3a+b)x^2+(a-2b)x+b+2c = 11x^2-x+4, find the values of a, b and c
could you please describe how to do this in detail as I am stuck.
Thanks in advance, glenn.
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#2 2008-04-12 01:33:53
- mathsyperson
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- Registered: 2005-06-22
- Posts: 4,900
Re: Polynomial Identities
The key thing here is that you have an identity, not an equality. That means that the statement is always true, no matter what value x takes.
Because of this, the coefficients in front of x² and x and the constant terms all need to match up. So pairing these against each other, you get:
3a+b = 11
a-2b = -1
b+2c = 4
Solve the first two equations simultaneously to get a and b, then use b with the third equation to find c.
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#3 2008-04-12 14:52:57
- glenn101
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- Registered: 2008-04-02
- Posts: 108
Re: Polynomial Identities
thank you mathsyperson, thats exactly what I needed:D
Last edited by glenn101 (2008-04-12 14:53:09)
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