Solve for b
b=\frac{\sqrt{5}-1}{20}\approx 0.061803399
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\left(2+\sqrt{20}\right)b=\frac{1}{5}\times 2^{\frac{1}{2}}\times 1\sqrt{2}
Multiply both sides of the equation by 2.
\left(2+2\sqrt{5}\right)b=\frac{1}{5}\times 2^{\frac{1}{2}}\times 1\sqrt{2}
Factor 20=2^{2}\times 5. Rewrite the square root of the product \sqrt{2^{2}\times 5} as the product of square roots \sqrt{2^{2}}\sqrt{5}. Take the square root of 2^{2}.
2b+2\sqrt{5}b=\frac{1}{5}\times 2^{\frac{1}{2}}\times 1\sqrt{2}
Use the distributive property to multiply 2+2\sqrt{5} by b.
2b+2\sqrt{5}b=\frac{1}{5}\times 2^{\frac{1}{2}}\sqrt{2}
Multiply \frac{1}{5} and 1 to get \frac{1}{5}.
2\sqrt{5}b+2b=\frac{1}{5}\sqrt{2}\sqrt{2}
Reorder the terms.
2\sqrt{5}b+2b=\frac{1}{5}\times 2
Multiply \sqrt{2} and \sqrt{2} to get 2.
2\sqrt{5}b+2b=\frac{2}{5}
Multiply \frac{1}{5} and 2 to get \frac{2}{5}.
\left(2\sqrt{5}+2\right)b=\frac{2}{5}
Combine all terms containing b.
\frac{\left(2\sqrt{5}+2\right)b}{2\sqrt{5}+2}=\frac{\frac{2}{5}}{2\sqrt{5}+2}
Divide both sides by 2\sqrt{5}+2.
b=\frac{\frac{2}{5}}{2\sqrt{5}+2}
Dividing by 2\sqrt{5}+2 undoes the multiplication by 2\sqrt{5}+2.
b=\frac{\sqrt{5}-1}{20}
Divide \frac{2}{5} by 2\sqrt{5}+2.
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