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# Newton Raphson question watch

1. Find the root of the function y = x3 + 4x2 + 7 in the vicinity of x = −4 correct to 5decimal places.
I have got so far:Let f(x)= x^3+4x^2+7

f'(x)= 3x^2+8x

Xn+1= Xn-f(xn)/f'(xn) => Xn+1= Xn-x^3-4x^2+7/3x^2-8x

x=-4, -4-(-4^3+4x-4^2+7)/(3x-4^2-8x-4)= -4.0875On the right track?
2. (Original post by trollenduser)
Find the root of the function y = x3 + 4x2 + 7 in the vicinity of x = −4 correct to 5decimal places.
I have got so far:Let f(x)= x^3+4x^2+7

f'(x)= 3x^2+8x

Xn+1= Xn-f(xn)/f'(xn) => Xn+1= Xn-x^3-4x^2+7/3x^2-8x

x=-4, -4-(-4^3+4x-4^2+7)/(3x-4^2-8x-4)= -4.0875On the right track?
Keep plugging -4.0875 along with the rest of those digits that you havent mentioned back into that equation, use the answer function on your calculator to speed it up, but yes the right track I believe.
3. Yes, you are on the right track. However, should you need to find more estimates, only round at the end.
4. wait what you guys have newton raphson exam questions? I thought it was a coursework thing
5. (Original post by CancerousProblem)
wait what you guys have newton raphson exam questions? I thought it was a coursework thing
Yeah you get it in FP1 for Edexcel.
There is no coursework for Edexcel.
6. (Original post by CancerousProblem)
wait what you guys have newton raphson exam questions? I thought it was a coursework thing
(Original post by rayquaza17)
Yeah you get it in FP1 for Edexcel.
There is no coursework for Edexcel.
Also Numerical Methods for OCR MEI. What a nightmare...

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