Solve for a
a=\frac{9}{11}\approx 0.818181818
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\frac{\left(3-\sqrt{5}\right)\left(3-2\sqrt{5}\right)}{\left(3+2\sqrt{5}\right)\left(3-2\sqrt{5}\right)}=-\frac{19}{11}+a\sqrt{5}
Rationalize the denominator of \frac{3-\sqrt{5}}{3+2\sqrt{5}} by multiplying numerator and denominator by 3-2\sqrt{5}.
\frac{\left(3-\sqrt{5}\right)\left(3-2\sqrt{5}\right)}{3^{2}-\left(2\sqrt{5}\right)^{2}}=-\frac{19}{11}+a\sqrt{5}
Consider \left(3+2\sqrt{5}\right)\left(3-2\sqrt{5}\right). Multiplication can be transformed into difference of squares using the rule: \left(a-b\right)\left(a+b\right)=a^{2}-b^{2}.
\frac{\left(3-\sqrt{5}\right)\left(3-2\sqrt{5}\right)}{9-\left(2\sqrt{5}\right)^{2}}=-\frac{19}{11}+a\sqrt{5}
Calculate 3 to the power of 2 and get 9.
\frac{\left(3-\sqrt{5}\right)\left(3-2\sqrt{5}\right)}{9-2^{2}\left(\sqrt{5}\right)^{2}}=-\frac{19}{11}+a\sqrt{5}
Expand \left(2\sqrt{5}\right)^{2}.
\frac{\left(3-\sqrt{5}\right)\left(3-2\sqrt{5}\right)}{9-4\left(\sqrt{5}\right)^{2}}=-\frac{19}{11}+a\sqrt{5}
Calculate 2 to the power of 2 and get 4.
\frac{\left(3-\sqrt{5}\right)\left(3-2\sqrt{5}\right)}{9-4\times 5}=-\frac{19}{11}+a\sqrt{5}
The square of \sqrt{5} is 5.
\frac{\left(3-\sqrt{5}\right)\left(3-2\sqrt{5}\right)}{9-20}=-\frac{19}{11}+a\sqrt{5}
Multiply 4 and 5 to get 20.
\frac{\left(3-\sqrt{5}\right)\left(3-2\sqrt{5}\right)}{-11}=-\frac{19}{11}+a\sqrt{5}
Subtract 20 from 9 to get -11.
\frac{9-6\sqrt{5}-3\sqrt{5}+2\left(\sqrt{5}\right)^{2}}{-11}=-\frac{19}{11}+a\sqrt{5}
Apply the distributive property by multiplying each term of 3-\sqrt{5} by each term of 3-2\sqrt{5}.
\frac{9-9\sqrt{5}+2\left(\sqrt{5}\right)^{2}}{-11}=-\frac{19}{11}+a\sqrt{5}
Combine -6\sqrt{5} and -3\sqrt{5} to get -9\sqrt{5}.
\frac{9-9\sqrt{5}+2\times 5}{-11}=-\frac{19}{11}+a\sqrt{5}
The square of \sqrt{5} is 5.
\frac{9-9\sqrt{5}+10}{-11}=-\frac{19}{11}+a\sqrt{5}
Multiply 2 and 5 to get 10.
\frac{19-9\sqrt{5}}{-11}=-\frac{19}{11}+a\sqrt{5}
Add 9 and 10 to get 19.
\frac{-19+9\sqrt{5}}{11}=-\frac{19}{11}+a\sqrt{5}
Multiply both numerator and denominator by -1.
-\frac{19}{11}+\frac{9}{11}\sqrt{5}=-\frac{19}{11}+a\sqrt{5}
Divide each term of -19+9\sqrt{5} by 11 to get -\frac{19}{11}+\frac{9}{11}\sqrt{5}.
-\frac{19}{11}+a\sqrt{5}=-\frac{19}{11}+\frac{9}{11}\sqrt{5}
Swap sides so that all variable terms are on the left hand side.
a\sqrt{5}=-\frac{19}{11}+\frac{9}{11}\sqrt{5}+\frac{19}{11}
Add \frac{19}{11} to both sides.
a\sqrt{5}=\frac{9}{11}\sqrt{5}
Add -\frac{19}{11} and \frac{19}{11} to get 0.
\sqrt{5}a=\frac{9\sqrt{5}}{11}
The equation is in standard form.
\frac{\sqrt{5}a}{\sqrt{5}}=\frac{9\sqrt{5}}{11\sqrt{5}}
Divide both sides by \sqrt{5}.
a=\frac{9\sqrt{5}}{11\sqrt{5}}
Dividing by \sqrt{5} undoes the multiplication by \sqrt{5}.
a=\frac{9}{11}
Divide \frac{9\sqrt{5}}{11} by \sqrt{5}.
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