Evaluating expression with Integer part and Fraction part of a nested radical
$begingroup$
Let
$$A= sqrt{93+28sqrt{11}}$$
if $B$ is the integer part of $A$ and $C$ is the fraction part of $C$, what is the value of
$$B+C^2$$
I tried manipulating it by setting
$$ A=B+C$$
but I can't transform it into the expression, do I need approximate the integer part of A in order to solve this or is there another way?
radicals
$endgroup$
add a comment |
$begingroup$
Let
$$A= sqrt{93+28sqrt{11}}$$
if $B$ is the integer part of $A$ and $C$ is the fraction part of $C$, what is the value of
$$B+C^2$$
I tried manipulating it by setting
$$ A=B+C$$
but I can't transform it into the expression, do I need approximate the integer part of A in order to solve this or is there another way?
radicals
$endgroup$
$begingroup$
Presumably you mean $C$ is the fractional part of $A$
$endgroup$
– Ross Millikan
Mar 23 at 14:07
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What do you mean by fractional part? That number is irrational.
$endgroup$
– Allawonder
Mar 23 at 14:10
add a comment |
$begingroup$
Let
$$A= sqrt{93+28sqrt{11}}$$
if $B$ is the integer part of $A$ and $C$ is the fraction part of $C$, what is the value of
$$B+C^2$$
I tried manipulating it by setting
$$ A=B+C$$
but I can't transform it into the expression, do I need approximate the integer part of A in order to solve this or is there another way?
radicals
$endgroup$
Let
$$A= sqrt{93+28sqrt{11}}$$
if $B$ is the integer part of $A$ and $C$ is the fraction part of $C$, what is the value of
$$B+C^2$$
I tried manipulating it by setting
$$ A=B+C$$
but I can't transform it into the expression, do I need approximate the integer part of A in order to solve this or is there another way?
radicals
radicals
edited Mar 23 at 14:59
Maria Mazur
49.3k1360123
49.3k1360123
asked Mar 23 at 13:51
SuperMage1SuperMage1
947211
947211
$begingroup$
Presumably you mean $C$ is the fractional part of $A$
$endgroup$
– Ross Millikan
Mar 23 at 14:07
$begingroup$
What do you mean by fractional part? That number is irrational.
$endgroup$
– Allawonder
Mar 23 at 14:10
add a comment |
$begingroup$
Presumably you mean $C$ is the fractional part of $A$
$endgroup$
– Ross Millikan
Mar 23 at 14:07
$begingroup$
What do you mean by fractional part? That number is irrational.
$endgroup$
– Allawonder
Mar 23 at 14:10
$begingroup$
Presumably you mean $C$ is the fractional part of $A$
$endgroup$
– Ross Millikan
Mar 23 at 14:07
$begingroup$
Presumably you mean $C$ is the fractional part of $A$
$endgroup$
– Ross Millikan
Mar 23 at 14:07
$begingroup$
What do you mean by fractional part? That number is irrational.
$endgroup$
– Allawonder
Mar 23 at 14:10
$begingroup$
What do you mean by fractional part? That number is irrational.
$endgroup$
– Allawonder
Mar 23 at 14:10
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
Let's find intgers $x,y$ such that $$(x+ysqrt{11})^2= 93+28sqrt{11}$$
Then $$x^2+11y^2 =93 ;;;wedge ;;; 2xy = 28$$
Since $11y^2<99implies y^2 <9 implies |y|leq 2$ and $xy=14$. Playing with numbers we see that $x=7$ and $y=2$ works well, so $$boxed{sqrt{93+28sqrt{11}} = 7+2sqrt{11}}$$
Since $$13= 7+2cdot 3<7+2sqrt{11} <7+2cdot sqrt{49over 4} = 14$$
we see $B =13$...
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add a comment |
$begingroup$
Hint:
$(7+2sqrt{11})^2=cdots$
$endgroup$
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
$begingroup$
Let's find intgers $x,y$ such that $$(x+ysqrt{11})^2= 93+28sqrt{11}$$
Then $$x^2+11y^2 =93 ;;;wedge ;;; 2xy = 28$$
Since $11y^2<99implies y^2 <9 implies |y|leq 2$ and $xy=14$. Playing with numbers we see that $x=7$ and $y=2$ works well, so $$boxed{sqrt{93+28sqrt{11}} = 7+2sqrt{11}}$$
Since $$13= 7+2cdot 3<7+2sqrt{11} <7+2cdot sqrt{49over 4} = 14$$
we see $B =13$...
$endgroup$
add a comment |
$begingroup$
Let's find intgers $x,y$ such that $$(x+ysqrt{11})^2= 93+28sqrt{11}$$
Then $$x^2+11y^2 =93 ;;;wedge ;;; 2xy = 28$$
Since $11y^2<99implies y^2 <9 implies |y|leq 2$ and $xy=14$. Playing with numbers we see that $x=7$ and $y=2$ works well, so $$boxed{sqrt{93+28sqrt{11}} = 7+2sqrt{11}}$$
Since $$13= 7+2cdot 3<7+2sqrt{11} <7+2cdot sqrt{49over 4} = 14$$
we see $B =13$...
$endgroup$
add a comment |
$begingroup$
Let's find intgers $x,y$ such that $$(x+ysqrt{11})^2= 93+28sqrt{11}$$
Then $$x^2+11y^2 =93 ;;;wedge ;;; 2xy = 28$$
Since $11y^2<99implies y^2 <9 implies |y|leq 2$ and $xy=14$. Playing with numbers we see that $x=7$ and $y=2$ works well, so $$boxed{sqrt{93+28sqrt{11}} = 7+2sqrt{11}}$$
Since $$13= 7+2cdot 3<7+2sqrt{11} <7+2cdot sqrt{49over 4} = 14$$
we see $B =13$...
$endgroup$
Let's find intgers $x,y$ such that $$(x+ysqrt{11})^2= 93+28sqrt{11}$$
Then $$x^2+11y^2 =93 ;;;wedge ;;; 2xy = 28$$
Since $11y^2<99implies y^2 <9 implies |y|leq 2$ and $xy=14$. Playing with numbers we see that $x=7$ and $y=2$ works well, so $$boxed{sqrt{93+28sqrt{11}} = 7+2sqrt{11}}$$
Since $$13= 7+2cdot 3<7+2sqrt{11} <7+2cdot sqrt{49over 4} = 14$$
we see $B =13$...
answered Mar 23 at 14:20
Maria MazurMaria Mazur
49.3k1360123
49.3k1360123
add a comment |
add a comment |
$begingroup$
Hint:
$(7+2sqrt{11})^2=cdots$
$endgroup$
add a comment |
$begingroup$
Hint:
$(7+2sqrt{11})^2=cdots$
$endgroup$
add a comment |
$begingroup$
Hint:
$(7+2sqrt{11})^2=cdots$
$endgroup$
Hint:
$(7+2sqrt{11})^2=cdots$
answered Mar 23 at 14:05
drhabdrhab
104k545136
104k545136
add a comment |
add a comment |
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$begingroup$
Presumably you mean $C$ is the fractional part of $A$
$endgroup$
– Ross Millikan
Mar 23 at 14:07
$begingroup$
What do you mean by fractional part? That number is irrational.
$endgroup$
– Allawonder
Mar 23 at 14:10