Pure Mathematics
Statistics

Worked Example 5

A sequence of negative numbers is defined by [latex]{{x}_{n+1}}=-\sqrt{8+3{{x}_{n}}}[/latex] for [latex]n=1[/latex], [latex]2[/latex], [latex]3[/latex], …

(i)

Show that [latex]-\frac{8}{3}<{{x}_{n}}<0[/latex] for [latex]n=1[/latex], [latex]2[/latex], [latex]3[/latex], …

(ii)

Find the exact value of [latex]l[/latex], given that when [latex]n\to \infty [/latex], [latex]{{x}_{n}}\to l[/latex].

(iii)

Show that [latex]{{x}_{n+1}}^{2}-{{l}^{2}}=3\left( {{x}_{n}}-l \right)[/latex].

(iv)

Show algebraically that if [latex]{{x}_{n}}<l[/latex] for some value of [latex]n[/latex], then [latex]{{x}_{n+1}}>l[/latex].

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