C4 quick question
Maths and statistics discussion, revision, exam and homework help.
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Re: C4 quick questionOr if it wasn't so obvious to find, the first root, you could use the Newton-Raphson method:(Original post by BabyMaths)
p^3-21p-20=0
Look at the coeffficients. 1, -21, -20.
With p=-1 you have -1+21-20=0.
Next you could divide by p+1.
But then once the first root is found, divide through and solve the quadratic. -
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Re: C4 quick questionHow do you know when you've found a root with the newton raphson method?(Original post by Transcendence)
Or if it wasn't so obvious to find, the first root, you could use the Newton-Raphson method:
But then once the first root is found, divide through and solve the quadratic. -
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Re: C4 quick questionIt doesn't find roots, it approximates them.(Original post by Super Mario 64)
How do you know when you've found a root with the newton raphson method? -
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Re: C4 quick questionWhen the answer on the calculator doesn't change, you've found one though tbh. It will approximate though, like he said.(Original post by james22)
It doesn't find roots, it approximates them. -
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Re: C4 quick questionDo it by inspection.(Original post by Super Mario 64)
How do you know when you've found a root with the newton raphson method?
Newton-Raphson is in FP1, if you are doing edexcel, so it isn't required for C4.
You may like to read about rational root theorem if you struggle to find the obvious root. -
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Re: C4 quick questionIt will take too long, its best done by inspection.(Original post by Transcendence)
When the answer on the calculator doesn't change, you've found one though tbh. It will approximate though, like he said. -
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Re: C4 quick questionis inspection basically trial and error?(Original post by raheem94)
It will take too long, its best done by inspection. -
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Re: C4 quick questionYes. You can just try in some values and see which one is the factor.(Original post by Super Mario 64)
is inspection basically trial and error?
Or if you have a fx-991es, it can automatically find the roots of a cubic.
