How to convert any decimal number in form of $sqrt a+sqrt b$?
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Is there any method to directly convert any decimal number in form of $sqrt a+sqrt b$, given a and b are integers? Like $4.88=sqrt5+sqrt7$ (approximately)
irrational-numbers
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add a comment |
$begingroup$
Is there any method to directly convert any decimal number in form of $sqrt a+sqrt b$, given a and b are integers? Like $4.88=sqrt5+sqrt7$ (approximately)
irrational-numbers
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1
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$4.88 neq sqrt 5 + sqrt 7$ LHS is rational, RHS is irrational. If you'd written $4.88 approx sqrt 5 + sqrt 7$ that would be acceptable.
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– Deepak
Dec 2 '18 at 3:16
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@martha Do you mean to convert any rational number?
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– Toby Mak
Dec 2 '18 at 3:41
2
$begingroup$
If $r=sqrt a+sqrt b$, then $rgesqrt a$, so $ale r^2$, and similarly $ble r^2$. So if worst comes to worst you can just check every pair $(a,b)$ up to $r^2$ to see which one comes closest. Not quite as bad as it sounds, as for each value of $a$ that you try, you can compute $(r-sqrt a)^2$ to see what value of $b$ to try.
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– Gerry Myerson
Dec 2 '18 at 3:48
add a comment |
$begingroup$
Is there any method to directly convert any decimal number in form of $sqrt a+sqrt b$, given a and b are integers? Like $4.88=sqrt5+sqrt7$ (approximately)
irrational-numbers
$endgroup$
Is there any method to directly convert any decimal number in form of $sqrt a+sqrt b$, given a and b are integers? Like $4.88=sqrt5+sqrt7$ (approximately)
irrational-numbers
irrational-numbers
edited Dec 2 '18 at 7:21
Tianlalu
3,08121038
3,08121038
asked Dec 2 '18 at 3:14
marthamartha
71
71
1
$begingroup$
$4.88 neq sqrt 5 + sqrt 7$ LHS is rational, RHS is irrational. If you'd written $4.88 approx sqrt 5 + sqrt 7$ that would be acceptable.
$endgroup$
– Deepak
Dec 2 '18 at 3:16
$begingroup$
@martha Do you mean to convert any rational number?
$endgroup$
– Toby Mak
Dec 2 '18 at 3:41
2
$begingroup$
If $r=sqrt a+sqrt b$, then $rgesqrt a$, so $ale r^2$, and similarly $ble r^2$. So if worst comes to worst you can just check every pair $(a,b)$ up to $r^2$ to see which one comes closest. Not quite as bad as it sounds, as for each value of $a$ that you try, you can compute $(r-sqrt a)^2$ to see what value of $b$ to try.
$endgroup$
– Gerry Myerson
Dec 2 '18 at 3:48
add a comment |
1
$begingroup$
$4.88 neq sqrt 5 + sqrt 7$ LHS is rational, RHS is irrational. If you'd written $4.88 approx sqrt 5 + sqrt 7$ that would be acceptable.
$endgroup$
– Deepak
Dec 2 '18 at 3:16
$begingroup$
@martha Do you mean to convert any rational number?
$endgroup$
– Toby Mak
Dec 2 '18 at 3:41
2
$begingroup$
If $r=sqrt a+sqrt b$, then $rgesqrt a$, so $ale r^2$, and similarly $ble r^2$. So if worst comes to worst you can just check every pair $(a,b)$ up to $r^2$ to see which one comes closest. Not quite as bad as it sounds, as for each value of $a$ that you try, you can compute $(r-sqrt a)^2$ to see what value of $b$ to try.
$endgroup$
– Gerry Myerson
Dec 2 '18 at 3:48
1
1
$begingroup$
$4.88 neq sqrt 5 + sqrt 7$ LHS is rational, RHS is irrational. If you'd written $4.88 approx sqrt 5 + sqrt 7$ that would be acceptable.
$endgroup$
– Deepak
Dec 2 '18 at 3:16
$begingroup$
$4.88 neq sqrt 5 + sqrt 7$ LHS is rational, RHS is irrational. If you'd written $4.88 approx sqrt 5 + sqrt 7$ that would be acceptable.
$endgroup$
– Deepak
Dec 2 '18 at 3:16
$begingroup$
@martha Do you mean to convert any rational number?
$endgroup$
– Toby Mak
Dec 2 '18 at 3:41
$begingroup$
@martha Do you mean to convert any rational number?
$endgroup$
– Toby Mak
Dec 2 '18 at 3:41
2
2
$begingroup$
If $r=sqrt a+sqrt b$, then $rgesqrt a$, so $ale r^2$, and similarly $ble r^2$. So if worst comes to worst you can just check every pair $(a,b)$ up to $r^2$ to see which one comes closest. Not quite as bad as it sounds, as for each value of $a$ that you try, you can compute $(r-sqrt a)^2$ to see what value of $b$ to try.
$endgroup$
– Gerry Myerson
Dec 2 '18 at 3:48
$begingroup$
If $r=sqrt a+sqrt b$, then $rgesqrt a$, so $ale r^2$, and similarly $ble r^2$. So if worst comes to worst you can just check every pair $(a,b)$ up to $r^2$ to see which one comes closest. Not quite as bad as it sounds, as for each value of $a$ that you try, you can compute $(r-sqrt a)^2$ to see what value of $b$ to try.
$endgroup$
– Gerry Myerson
Dec 2 '18 at 3:48
add a comment |
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1
$begingroup$
$4.88 neq sqrt 5 + sqrt 7$ LHS is rational, RHS is irrational. If you'd written $4.88 approx sqrt 5 + sqrt 7$ that would be acceptable.
$endgroup$
– Deepak
Dec 2 '18 at 3:16
$begingroup$
@martha Do you mean to convert any rational number?
$endgroup$
– Toby Mak
Dec 2 '18 at 3:41
2
$begingroup$
If $r=sqrt a+sqrt b$, then $rgesqrt a$, so $ale r^2$, and similarly $ble r^2$. So if worst comes to worst you can just check every pair $(a,b)$ up to $r^2$ to see which one comes closest. Not quite as bad as it sounds, as for each value of $a$ that you try, you can compute $(r-sqrt a)^2$ to see what value of $b$ to try.
$endgroup$
– Gerry Myerson
Dec 2 '18 at 3:48