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How to find the values of a,b and c?

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  • How to find the values of a,b and c?


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Answer #1 | 23/12 2013 06:04
You need to do a bit of algebra to solve, using the information from the question. Start with 0,3, so we know from this that: 3 = a(0^2) + b0 + c 3 = c Also 1,-2 so: -2 = a(1^2) + b1 + c -2 = a + b + c we already know c = 3 so: -2 = a + b + 3 rearranging: a+b = -5 Finally, we know the gradient at 0,3 is -3 so we'll calculate the derivative: dy/dx = 2ax + b -3 = 2a(0) + b So we know b = -3. Now we can solve from that and the earlier equations: a+b = -5 a-3 = -5 a = -2 So that's: y = -2x^2 - 3x + 3 You can see what it looks like here: http://www.wolframalpha.com/input/?i=y+%3D+-2x^2+-+3x+%2B+3

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