What is $int_0^{1}frac{x^{300}}{1+x^2+x^3}dx$ upto $2$ decimal places?
$begingroup$
In an examination, I was asked to calculate $int_0^{1}frac{x^{300}}{1+x^2+x^3}dx$. Options were gives as
a - 0.00
b - 0.02
c - 0.10
d - 0.33
e - 1.00
Just look at the questions I felt the integral $I geq sum_0^1{}frac{x^{300}}{1+x^2+x^3} = 0.33$. I felt, since numerator is very small as compared to denominator therefore, for value $epsilon<1$, $1.00 $ isn't possible. So, I chose option d. But I am not sure whether its correct or not as I didn't follow standard procedure.
what is the correct answer and How can it be solved using a standard procedure?
integration
$endgroup$
add a comment |
$begingroup$
In an examination, I was asked to calculate $int_0^{1}frac{x^{300}}{1+x^2+x^3}dx$. Options were gives as
a - 0.00
b - 0.02
c - 0.10
d - 0.33
e - 1.00
Just look at the questions I felt the integral $I geq sum_0^1{}frac{x^{300}}{1+x^2+x^3} = 0.33$. I felt, since numerator is very small as compared to denominator therefore, for value $epsilon<1$, $1.00 $ isn't possible. So, I chose option d. But I am not sure whether its correct or not as I didn't follow standard procedure.
what is the correct answer and How can it be solved using a standard procedure?
integration
$endgroup$
add a comment |
$begingroup$
In an examination, I was asked to calculate $int_0^{1}frac{x^{300}}{1+x^2+x^3}dx$. Options were gives as
a - 0.00
b - 0.02
c - 0.10
d - 0.33
e - 1.00
Just look at the questions I felt the integral $I geq sum_0^1{}frac{x^{300}}{1+x^2+x^3} = 0.33$. I felt, since numerator is very small as compared to denominator therefore, for value $epsilon<1$, $1.00 $ isn't possible. So, I chose option d. But I am not sure whether its correct or not as I didn't follow standard procedure.
what is the correct answer and How can it be solved using a standard procedure?
integration
$endgroup$
In an examination, I was asked to calculate $int_0^{1}frac{x^{300}}{1+x^2+x^3}dx$. Options were gives as
a - 0.00
b - 0.02
c - 0.10
d - 0.33
e - 1.00
Just look at the questions I felt the integral $I geq sum_0^1{}frac{x^{300}}{1+x^2+x^3} = 0.33$. I felt, since numerator is very small as compared to denominator therefore, for value $epsilon<1$, $1.00 $ isn't possible. So, I chose option d. But I am not sure whether its correct or not as I didn't follow standard procedure.
what is the correct answer and How can it be solved using a standard procedure?
integration
integration
edited Dec 19 '18 at 11:44
Mr.Sigma.
asked Dec 19 '18 at 11:02
Mr.Sigma.Mr.Sigma.
18310
18310
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
Since $1+x^2+x^3 ge 1$ for $x ge 0$, we have
$$
int_0^{1}frac{x^{300}}{1+x^2+x^3} , dx
le
int_0^{1}x^{300} , dx
=frac{1}{301}
<frac{1}{300}
=0.00333cdots
$$
This is enough to answer the question.
A little more work gives a good estimate of the integral.
Since $1+x^2+x^3 le 3$ for $x ge 0$, we have
$$
int_0^{1}frac{x^{300}}{1+x^2+x^3} , dx
ge
int_0^{1} frac{1}{3} x^{300} , dx
=frac{1}{903}
$$
Thus
$$
0.001107
<
frac{1}{903}
le
int_0^{1}frac{x^{300}}{1+x^2+x^3} , dx
le
frac{1}{301}
<
0.003323
$$
$endgroup$
1
$begingroup$
The integral is approximately $0.00111357$ according to WA.
$endgroup$
– lhf
Dec 19 '18 at 11:27
$begingroup$
I liked the way you solved. Thanks for the help. :)
$endgroup$
– Mr.Sigma.
Dec 19 '18 at 11:46
add a comment |
$begingroup$
Since $frac{x^{300}}{1+x^2+x^3}$ has a zero of order $300$ at the origin, most of the mass of the integral $int_{0}^{1}frac{x^{300}}{1+x^2+x^3},dx$ comes from a neighbourhood of the right endpoint of the integration range. Obviously $int_{0}^{1}frac{x^{300}}{3},dx=frac{1}{903}$, and
$$ I-frac{1}{903}=int_{0}^{1}x^{300}left(frac{1}{1+x^2+x^3}-frac{1}{3}right),dx =int_{0}^{1}x^{300}(1-x)frac{2+2x+x^2}{3(1+x^2+x^3)},dx$$
is bounded by
$$ int_{0}^{1}x^{300}(1-x),dx = frac{1}{301cdot 302} $$
hence the wanted integral is $color{green}{0.0011}$(unknown digits).
$endgroup$
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
Since $1+x^2+x^3 ge 1$ for $x ge 0$, we have
$$
int_0^{1}frac{x^{300}}{1+x^2+x^3} , dx
le
int_0^{1}x^{300} , dx
=frac{1}{301}
<frac{1}{300}
=0.00333cdots
$$
This is enough to answer the question.
A little more work gives a good estimate of the integral.
Since $1+x^2+x^3 le 3$ for $x ge 0$, we have
$$
int_0^{1}frac{x^{300}}{1+x^2+x^3} , dx
ge
int_0^{1} frac{1}{3} x^{300} , dx
=frac{1}{903}
$$
Thus
$$
0.001107
<
frac{1}{903}
le
int_0^{1}frac{x^{300}}{1+x^2+x^3} , dx
le
frac{1}{301}
<
0.003323
$$
$endgroup$
1
$begingroup$
The integral is approximately $0.00111357$ according to WA.
$endgroup$
– lhf
Dec 19 '18 at 11:27
$begingroup$
I liked the way you solved. Thanks for the help. :)
$endgroup$
– Mr.Sigma.
Dec 19 '18 at 11:46
add a comment |
$begingroup$
Since $1+x^2+x^3 ge 1$ for $x ge 0$, we have
$$
int_0^{1}frac{x^{300}}{1+x^2+x^3} , dx
le
int_0^{1}x^{300} , dx
=frac{1}{301}
<frac{1}{300}
=0.00333cdots
$$
This is enough to answer the question.
A little more work gives a good estimate of the integral.
Since $1+x^2+x^3 le 3$ for $x ge 0$, we have
$$
int_0^{1}frac{x^{300}}{1+x^2+x^3} , dx
ge
int_0^{1} frac{1}{3} x^{300} , dx
=frac{1}{903}
$$
Thus
$$
0.001107
<
frac{1}{903}
le
int_0^{1}frac{x^{300}}{1+x^2+x^3} , dx
le
frac{1}{301}
<
0.003323
$$
$endgroup$
1
$begingroup$
The integral is approximately $0.00111357$ according to WA.
$endgroup$
– lhf
Dec 19 '18 at 11:27
$begingroup$
I liked the way you solved. Thanks for the help. :)
$endgroup$
– Mr.Sigma.
Dec 19 '18 at 11:46
add a comment |
$begingroup$
Since $1+x^2+x^3 ge 1$ for $x ge 0$, we have
$$
int_0^{1}frac{x^{300}}{1+x^2+x^3} , dx
le
int_0^{1}x^{300} , dx
=frac{1}{301}
<frac{1}{300}
=0.00333cdots
$$
This is enough to answer the question.
A little more work gives a good estimate of the integral.
Since $1+x^2+x^3 le 3$ for $x ge 0$, we have
$$
int_0^{1}frac{x^{300}}{1+x^2+x^3} , dx
ge
int_0^{1} frac{1}{3} x^{300} , dx
=frac{1}{903}
$$
Thus
$$
0.001107
<
frac{1}{903}
le
int_0^{1}frac{x^{300}}{1+x^2+x^3} , dx
le
frac{1}{301}
<
0.003323
$$
$endgroup$
Since $1+x^2+x^3 ge 1$ for $x ge 0$, we have
$$
int_0^{1}frac{x^{300}}{1+x^2+x^3} , dx
le
int_0^{1}x^{300} , dx
=frac{1}{301}
<frac{1}{300}
=0.00333cdots
$$
This is enough to answer the question.
A little more work gives a good estimate of the integral.
Since $1+x^2+x^3 le 3$ for $x ge 0$, we have
$$
int_0^{1}frac{x^{300}}{1+x^2+x^3} , dx
ge
int_0^{1} frac{1}{3} x^{300} , dx
=frac{1}{903}
$$
Thus
$$
0.001107
<
frac{1}{903}
le
int_0^{1}frac{x^{300}}{1+x^2+x^3} , dx
le
frac{1}{301}
<
0.003323
$$
edited Dec 19 '18 at 11:45
answered Dec 19 '18 at 11:21
lhflhf
166k10171396
166k10171396
1
$begingroup$
The integral is approximately $0.00111357$ according to WA.
$endgroup$
– lhf
Dec 19 '18 at 11:27
$begingroup$
I liked the way you solved. Thanks for the help. :)
$endgroup$
– Mr.Sigma.
Dec 19 '18 at 11:46
add a comment |
1
$begingroup$
The integral is approximately $0.00111357$ according to WA.
$endgroup$
– lhf
Dec 19 '18 at 11:27
$begingroup$
I liked the way you solved. Thanks for the help. :)
$endgroup$
– Mr.Sigma.
Dec 19 '18 at 11:46
1
1
$begingroup$
The integral is approximately $0.00111357$ according to WA.
$endgroup$
– lhf
Dec 19 '18 at 11:27
$begingroup$
The integral is approximately $0.00111357$ according to WA.
$endgroup$
– lhf
Dec 19 '18 at 11:27
$begingroup$
I liked the way you solved. Thanks for the help. :)
$endgroup$
– Mr.Sigma.
Dec 19 '18 at 11:46
$begingroup$
I liked the way you solved. Thanks for the help. :)
$endgroup$
– Mr.Sigma.
Dec 19 '18 at 11:46
add a comment |
$begingroup$
Since $frac{x^{300}}{1+x^2+x^3}$ has a zero of order $300$ at the origin, most of the mass of the integral $int_{0}^{1}frac{x^{300}}{1+x^2+x^3},dx$ comes from a neighbourhood of the right endpoint of the integration range. Obviously $int_{0}^{1}frac{x^{300}}{3},dx=frac{1}{903}$, and
$$ I-frac{1}{903}=int_{0}^{1}x^{300}left(frac{1}{1+x^2+x^3}-frac{1}{3}right),dx =int_{0}^{1}x^{300}(1-x)frac{2+2x+x^2}{3(1+x^2+x^3)},dx$$
is bounded by
$$ int_{0}^{1}x^{300}(1-x),dx = frac{1}{301cdot 302} $$
hence the wanted integral is $color{green}{0.0011}$(unknown digits).
$endgroup$
add a comment |
$begingroup$
Since $frac{x^{300}}{1+x^2+x^3}$ has a zero of order $300$ at the origin, most of the mass of the integral $int_{0}^{1}frac{x^{300}}{1+x^2+x^3},dx$ comes from a neighbourhood of the right endpoint of the integration range. Obviously $int_{0}^{1}frac{x^{300}}{3},dx=frac{1}{903}$, and
$$ I-frac{1}{903}=int_{0}^{1}x^{300}left(frac{1}{1+x^2+x^3}-frac{1}{3}right),dx =int_{0}^{1}x^{300}(1-x)frac{2+2x+x^2}{3(1+x^2+x^3)},dx$$
is bounded by
$$ int_{0}^{1}x^{300}(1-x),dx = frac{1}{301cdot 302} $$
hence the wanted integral is $color{green}{0.0011}$(unknown digits).
$endgroup$
add a comment |
$begingroup$
Since $frac{x^{300}}{1+x^2+x^3}$ has a zero of order $300$ at the origin, most of the mass of the integral $int_{0}^{1}frac{x^{300}}{1+x^2+x^3},dx$ comes from a neighbourhood of the right endpoint of the integration range. Obviously $int_{0}^{1}frac{x^{300}}{3},dx=frac{1}{903}$, and
$$ I-frac{1}{903}=int_{0}^{1}x^{300}left(frac{1}{1+x^2+x^3}-frac{1}{3}right),dx =int_{0}^{1}x^{300}(1-x)frac{2+2x+x^2}{3(1+x^2+x^3)},dx$$
is bounded by
$$ int_{0}^{1}x^{300}(1-x),dx = frac{1}{301cdot 302} $$
hence the wanted integral is $color{green}{0.0011}$(unknown digits).
$endgroup$
Since $frac{x^{300}}{1+x^2+x^3}$ has a zero of order $300$ at the origin, most of the mass of the integral $int_{0}^{1}frac{x^{300}}{1+x^2+x^3},dx$ comes from a neighbourhood of the right endpoint of the integration range. Obviously $int_{0}^{1}frac{x^{300}}{3},dx=frac{1}{903}$, and
$$ I-frac{1}{903}=int_{0}^{1}x^{300}left(frac{1}{1+x^2+x^3}-frac{1}{3}right),dx =int_{0}^{1}x^{300}(1-x)frac{2+2x+x^2}{3(1+x^2+x^3)},dx$$
is bounded by
$$ int_{0}^{1}x^{300}(1-x),dx = frac{1}{301cdot 302} $$
hence the wanted integral is $color{green}{0.0011}$(unknown digits).
answered Dec 19 '18 at 23:47
Jack D'AurizioJack D'Aurizio
290k33282664
290k33282664
add a comment |
add a comment |
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