Solve for x
x=\frac{2\sqrt{5}}{5}\approx 0.894427191
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18x=36\sqrt{1-x^{2}}
Subtract 0 from both sides of the equation.
18x+0=36\sqrt{1-x^{2}}
Anything times zero gives zero.
18x=36\sqrt{1-x^{2}}
Anything plus zero gives itself.
\left(18x\right)^{2}=\left(36\sqrt{1-x^{2}}\right)^{2}
Square both sides of the equation.
18^{2}x^{2}=\left(36\sqrt{1-x^{2}}\right)^{2}
Expand \left(18x\right)^{2}.
324x^{2}=\left(36\sqrt{1-x^{2}}\right)^{2}
Calculate 18 to the power of 2 and get 324.
324x^{2}=36^{2}\left(\sqrt{1-x^{2}}\right)^{2}
Expand \left(36\sqrt{1-x^{2}}\right)^{2}.
324x^{2}=1296\left(\sqrt{1-x^{2}}\right)^{2}
Calculate 36 to the power of 2 and get 1296.
324x^{2}=1296\left(1-x^{2}\right)
Calculate \sqrt{1-x^{2}} to the power of 2 and get 1-x^{2}.
324x^{2}=1296-1296x^{2}
Use the distributive property to multiply 1296 by 1-x^{2}.
324x^{2}+1296x^{2}=1296
Add 1296x^{2} to both sides.
1620x^{2}=1296
Combine 324x^{2} and 1296x^{2} to get 1620x^{2}.
x^{2}=\frac{1296}{1620}
Divide both sides by 1620.
x^{2}=\frac{4}{5}
Reduce the fraction \frac{1296}{1620} to lowest terms by extracting and canceling out 324.
x=\frac{2\sqrt{5}}{5} x=-\frac{2\sqrt{5}}{5}
Take the square root of both sides of the equation.
18\times \frac{2\sqrt{5}}{5}=0\times \frac{2\sqrt{5}}{5}+36\sqrt{1-\left(\frac{2\sqrt{5}}{5}\right)^{2}}
Substitute \frac{2\sqrt{5}}{5} for x in the equation 18x=0x+36\sqrt{1-x^{2}}.
\frac{36}{5}\times 5^{\frac{1}{2}}=\frac{36}{5}\times 5^{\frac{1}{2}}
Simplify. The value x=\frac{2\sqrt{5}}{5} satisfies the equation.
18\left(-\frac{2\sqrt{5}}{5}\right)=0\left(-\frac{2\sqrt{5}}{5}\right)+36\sqrt{1-\left(-\frac{2\sqrt{5}}{5}\right)^{2}}
Substitute -\frac{2\sqrt{5}}{5} for x in the equation 18x=0x+36\sqrt{1-x^{2}}.
-\frac{36}{5}\times 5^{\frac{1}{2}}=\frac{36}{5}\times 5^{\frac{1}{2}}
Simplify. The value x=-\frac{2\sqrt{5}}{5} does not satisfy the equation because the left and the right hand side have opposite signs.
x=\frac{2\sqrt{5}}{5}
Equation 18x=36\sqrt{1-x^{2}} has a unique solution.
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