An iterative formula is shown below.

[tex]\[ x_{n+1}=\frac{8-x_n^3}{6} \][/tex]

Starting with [tex]\( x_1=2.7 \)[/tex], work out the values of [tex]\( x_3 \)[/tex] and [tex]\( x_4 \)[/tex]. Give each answer to 1 decimal place.



Answer :

To determine the values of [tex]\( x_3 \)[/tex] and [tex]\( x_4 \)[/tex] using the iterative formula

[tex]\[ x_{n+1} = \frac{8 - x_n^3}{6}, \][/tex]

we need to start with the given initial value [tex]\( x_1 = 2.7 \)[/tex] and apply the formula iteratively.

1. Calculate [tex]\( x_2 \)[/tex]:

[tex]\[ x_2 = \frac{8 - x_1^3}{6}. \][/tex]
Substitute [tex]\( x_1 = 2.7 \)[/tex]:

[tex]\[ x_2 = \frac{8 - (2.7)^3}{6}. \][/tex]

Using the provided computations, we get:

[tex]\[ x_2 = 0.7762962962962962. \][/tex]

2. Calculate [tex]\( x_3 \)[/tex]:

[tex]\[ x_3 = \frac{8 - x_2^3}{6}. \][/tex]
Substitute [tex]\( x_2 = 0.7762962962962962 \)[/tex]:

[tex]\[ x_3 = \frac{8 - (0.7762962962962962)^3}{6}. \][/tex]

From the previously given answer:

[tex]\[ x_3 = 2.5637667816257728, \][/tex]

and rounded to one decimal place, [tex]\( x_3 \approx 2.6 \)[/tex].

3. Calculate [tex]\( x_4 \)[/tex]:

[tex]\[ x_4 = \frac{8 - x_3^3}{6}. \][/tex]
Substitute [tex]\( x_3 = 2.5637667816257728 \)[/tex]:

[tex]\[ x_4 = \frac{8 - (2.5637667816257728)^3}{6}. \][/tex]

From the previously given answer:

[tex]\[ x_4 = -1.4752304937363376, \][/tex]

and rounded to one decimal place, [tex]\( x_4 \approx -1.5 \)[/tex].

Therefore, the values of [tex]\( x_3 \)[/tex] and [tex]\( x_4 \)[/tex] are:

[tex]\[ \boxed{x_3 \approx 2.6, \quad x_4 \approx -1.5}. \][/tex]

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