Understanding Lagrange error bound

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Estimating $ln(0.9)$ using a Taylor polynomial about $x=1$ what is the least degree of the polynomial that assures an error smaller than $0.0010$?



(The $n^th$ derivative of $(-1)^n-1cfrac(n-1!)x^n$ for $nge1$



Then Khan Academy says, the Lagrange bound for the error assures that $left|R_n(1.4)right|leleft|cfrac(-1)^ncfracn!z^n+1(n+1)!(1.4-1)^n+1right|$



Then it says $cfrac0.4^n+1(n+1)z^n+1lecfrac0.4^n+1(n+1)$



In the sentence before this one, why do they get rid of $z^n+1$?







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  • Because $1leq z$, therefore if you replace it by $1$ the denominator gets smaller, and the fraction larger. Take into account that I don't know what $R_n(1.4)$ and therefore, $z$, because you haven't defined it, but it looks like after you do, that is going to be the explanation.
    – user578878
    Jul 28 at 1:32















up vote
0
down vote

favorite












Estimating $ln(0.9)$ using a Taylor polynomial about $x=1$ what is the least degree of the polynomial that assures an error smaller than $0.0010$?



(The $n^th$ derivative of $(-1)^n-1cfrac(n-1!)x^n$ for $nge1$



Then Khan Academy says, the Lagrange bound for the error assures that $left|R_n(1.4)right|leleft|cfrac(-1)^ncfracn!z^n+1(n+1)!(1.4-1)^n+1right|$



Then it says $cfrac0.4^n+1(n+1)z^n+1lecfrac0.4^n+1(n+1)$



In the sentence before this one, why do they get rid of $z^n+1$?







share|cite|improve this question



















  • Because $1leq z$, therefore if you replace it by $1$ the denominator gets smaller, and the fraction larger. Take into account that I don't know what $R_n(1.4)$ and therefore, $z$, because you haven't defined it, but it looks like after you do, that is going to be the explanation.
    – user578878
    Jul 28 at 1:32













up vote
0
down vote

favorite









up vote
0
down vote

favorite











Estimating $ln(0.9)$ using a Taylor polynomial about $x=1$ what is the least degree of the polynomial that assures an error smaller than $0.0010$?



(The $n^th$ derivative of $(-1)^n-1cfrac(n-1!)x^n$ for $nge1$



Then Khan Academy says, the Lagrange bound for the error assures that $left|R_n(1.4)right|leleft|cfrac(-1)^ncfracn!z^n+1(n+1)!(1.4-1)^n+1right|$



Then it says $cfrac0.4^n+1(n+1)z^n+1lecfrac0.4^n+1(n+1)$



In the sentence before this one, why do they get rid of $z^n+1$?







share|cite|improve this question











Estimating $ln(0.9)$ using a Taylor polynomial about $x=1$ what is the least degree of the polynomial that assures an error smaller than $0.0010$?



(The $n^th$ derivative of $(-1)^n-1cfrac(n-1!)x^n$ for $nge1$



Then Khan Academy says, the Lagrange bound for the error assures that $left|R_n(1.4)right|leleft|cfrac(-1)^ncfracn!z^n+1(n+1)!(1.4-1)^n+1right|$



Then it says $cfrac0.4^n+1(n+1)z^n+1lecfrac0.4^n+1(n+1)$



In the sentence before this one, why do they get rid of $z^n+1$?









share|cite|improve this question










share|cite|improve this question




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asked Jul 28 at 1:30









Jinzu

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  • Because $1leq z$, therefore if you replace it by $1$ the denominator gets smaller, and the fraction larger. Take into account that I don't know what $R_n(1.4)$ and therefore, $z$, because you haven't defined it, but it looks like after you do, that is going to be the explanation.
    – user578878
    Jul 28 at 1:32

















  • Because $1leq z$, therefore if you replace it by $1$ the denominator gets smaller, and the fraction larger. Take into account that I don't know what $R_n(1.4)$ and therefore, $z$, because you haven't defined it, but it looks like after you do, that is going to be the explanation.
    – user578878
    Jul 28 at 1:32
















Because $1leq z$, therefore if you replace it by $1$ the denominator gets smaller, and the fraction larger. Take into account that I don't know what $R_n(1.4)$ and therefore, $z$, because you haven't defined it, but it looks like after you do, that is going to be the explanation.
– user578878
Jul 28 at 1:32





Because $1leq z$, therefore if you replace it by $1$ the denominator gets smaller, and the fraction larger. Take into account that I don't know what $R_n(1.4)$ and therefore, $z$, because you haven't defined it, but it looks like after you do, that is going to be the explanation.
– user578878
Jul 28 at 1:32
















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