Maths change of sign coursework
Extracts from this document...
Introduction
Osaamah Mohammed
Maths A2 Coursework
Change of Sign Method:-
3x3 – 6x + 1 = 0
Sketch: -
Looking at the graph we find that the roots lie between these intervals:
[-2,-1] [0,1] [1,2]
Finding root interval between [0,1] using a Decimal Search
Root [0 , 1]
X1 = 0
∴
Middle

0.17
-0.005261
Root [0.16 , 0.17]
X | f(X) |
0.16 | 0.052298 |
0.161 | 0.046520 |
0.162 | 0.040755 |
0.163 | 0.034992 |
0.164 | 0.029233 |
0.165 | 0.023476 |
0.166 | 0.017723 |
0.167 | 0.011972 |
0.168 | 0.0062249 |
0.169 | 0.00048043 |
0.170 | -0.005261 |
Root [0.169 , 0.170]
X | f(X) |
0.1690 | 0.00048043 |
0.1691 | -0.0000923852 |
Root [0.1690 , 0.1691]
X | f(X) |
0.1690 | 0.00048043 |
0.16901 | 0.00042299 |
0.16902 | 0.00036557 |
0.16903 | 0.00030814 |
0.16904 | 0.00025071 |
0.16905 | 0.00019328 |
0.16906 | 0.00013586 |
0.16907 | 0.00078427 |
0.16908 | 0.00021 |
0.16909 | -0.000036426 |
From this method we find that the root lies between[0.16908 , 0.16909]
∴ Root = 0.169085 ± 0.000005
testf (0.16908) = 0.00021
f (0.16909) = -0.000036426
There is a change
Conclusion
Start X1 = 0 Use Xn+1 = 2xn3 + 1
5
X2 = 2(0)3 + 1 = 0.2
5
X3 = 2(0.2)3 + 1 = 0.216
5
X4 = 2(0.216)3 + 1 = 0.22016
5
X5 = 0.22134
X6= 0.22169
X7 = 0.22179
X8 = 0.22182
X9 = 0.22183 root to 5 s.f (took 9 iterations)
X10 = 0.22183
Failure: -
Solve 2x3 – 5x + 1 = 0
Re-arrange this so that “X=….”
- 2x3 – 5x + 1 = 0
2x3 +1 = 5x
2x3 = 5x – 1
x3 = 5x – 1
2
x = (5x – 1)⅓
2
x = g(x)
Sketch : -
This student written piece of work is one of many that can be found in our AS and A Level Core & Pure Mathematics section.
Found what you're looking for?
- Start learning 29% faster today
- 150,000+ documents available
- Just £6.99 a month