Given the following function: f(x)=1.01e^(4x)-4.62e^(3x)-3.11e^(2x)+12.2e^(x)

Bevan Mcdonald

Bevan Mcdonald

Answered question

2020-10-19

Given the following function:
f(x)=1.01e4x4.62e3x3.11e2x+12.2ex
a) Use three-digit rounding frithmetic, the assumption that e1.53=4.62, and the fact that enx=(ex)n to evaluate f(1.53)
b) Redo the same calculation by first rewriting the equation using the polynomial factoring technique
c) Calculate the percentage relative errors in both part a) and b) to the true result f(1.53)=7.60787

Answer & Explanation

Laith Petty

Laith Petty

Skilled2020-10-20Added 103 answers

Step 1
a) f(x)=1.01e4x4.62e3x3.11e2x+12.2ex1.99
f(x)=1.01(ex)44.62(ex)33.11(ex)2+12.2ex1.99
f(1.53)=1.01(e1.53)44.62(e1.53)33.11(e1.53)2+12.2e1.531.99
=1.01(4.62)44.62(4.62)33.11(4.62)2+12.2(4.62)1.99
=1.01(455.583)4.62(98.611)3.11(21.344)+56.3641.99
=460.139455.58366.380+54.374
=7.45
Therefore, the value of f(1.53) obtained by this method is 7.45.
Step 2
b) The given function can be factorized as follows.
f(x)=1.01(ex+1.715)(ex0.173)(ex1.415)(ex4.702)
On substituting x=1.53 and using e1.53=4.62, we get
f(1.53)=1.01(4.62+1.715)(4.620.173)(4.621.415)(4.624.702)
=1.01(6.335)(4.447)(3.205)(0.082)
=7.478
Therefore, the value of f(1.53) obtained by this method is 7.478
Step 3
c) Percentage error δ is given by
δ=|VA  VEVE|
Here VA is the actual value observed and VE is the expected value which is -7.60787 in this case.
For the value obtained in part (a), the percentage error is
δa=|7.45+7.607877.60787| 100%
Jeffrey Jordon

Jeffrey Jordon

Expert2022-01-15Added 2605 answers

Answer is given below (on video)

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