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-\frac{1}{2}=\frac{30-a^{2}}{2-3\times 3}
Add 27 and 3 to get 30.
-\frac{1}{2}=\frac{30-a^{2}}{2-9}
Multiply 3 and 3 to get 9.
-\frac{1}{2}=\frac{30-a^{2}}{-7}
Subtract 9 from 2 to get -7.
-\frac{1}{2}=\frac{-30+a^{2}}{7}
Multiply both numerator and denominator by -1.
-\frac{1}{2}=-\frac{30}{7}+\frac{1}{7}a^{2}
Divide each term of -30+a^{2} by 7 to get -\frac{30}{7}+\frac{1}{7}a^{2}.
-\frac{30}{7}+\frac{1}{7}a^{2}=-\frac{1}{2}
Swap sides so that all variable terms are on the left hand side.
\frac{1}{7}a^{2}=-\frac{1}{2}+\frac{30}{7}
Add \frac{30}{7} to both sides.
\frac{1}{7}a^{2}=\frac{53}{14}
Add -\frac{1}{2} and \frac{30}{7} to get \frac{53}{14}.
a^{2}=\frac{53}{14}\times 7
Multiply both sides by 7, the reciprocal of \frac{1}{7}.
a^{2}=\frac{53}{2}
Multiply \frac{53}{14} and 7 to get \frac{53}{2}.
a=\frac{\sqrt{106}}{2} a=-\frac{\sqrt{106}}{2}
Take the square root of both sides of the equation.
-\frac{1}{2}=\frac{30-a^{2}}{2-3\times 3}
Add 27 and 3 to get 30.
-\frac{1}{2}=\frac{30-a^{2}}{2-9}
Multiply 3 and 3 to get 9.
-\frac{1}{2}=\frac{30-a^{2}}{-7}
Subtract 9 from 2 to get -7.
-\frac{1}{2}=\frac{-30+a^{2}}{7}
Multiply both numerator and denominator by -1.
-\frac{1}{2}=-\frac{30}{7}+\frac{1}{7}a^{2}
Divide each term of -30+a^{2} by 7 to get -\frac{30}{7}+\frac{1}{7}a^{2}.
-\frac{30}{7}+\frac{1}{7}a^{2}=-\frac{1}{2}
Swap sides so that all variable terms are on the left hand side.
-\frac{30}{7}+\frac{1}{7}a^{2}+\frac{1}{2}=0
Add \frac{1}{2} to both sides.
-\frac{53}{14}+\frac{1}{7}a^{2}=0
Add -\frac{30}{7} and \frac{1}{2} to get -\frac{53}{14}.
\frac{1}{7}a^{2}-\frac{53}{14}=0
Quadratic equations like this one, with an x^{2} term but no x term, can still be solved using the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}, once they are put in standard form: ax^{2}+bx+c=0.
a=\frac{0±\sqrt{0^{2}-4\times \frac{1}{7}\left(-\frac{53}{14}\right)}}{2\times \frac{1}{7}}
This equation is in standard form: ax^{2}+bx+c=0. Substitute \frac{1}{7} for a, 0 for b, and -\frac{53}{14} for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
a=\frac{0±\sqrt{-4\times \frac{1}{7}\left(-\frac{53}{14}\right)}}{2\times \frac{1}{7}}
Square 0.
a=\frac{0±\sqrt{-\frac{4}{7}\left(-\frac{53}{14}\right)}}{2\times \frac{1}{7}}
Multiply -4 times \frac{1}{7}.
a=\frac{0±\sqrt{\frac{106}{49}}}{2\times \frac{1}{7}}
Multiply -\frac{4}{7} times -\frac{53}{14} by multiplying numerator times numerator and denominator times denominator. Then reduce the fraction to lowest terms if possible.
a=\frac{0±\frac{\sqrt{106}}{7}}{2\times \frac{1}{7}}
Take the square root of \frac{106}{49}.
a=\frac{0±\frac{\sqrt{106}}{7}}{\frac{2}{7}}
Multiply 2 times \frac{1}{7}.
a=\frac{\sqrt{106}}{2}
Now solve the equation a=\frac{0±\frac{\sqrt{106}}{7}}{\frac{2}{7}} when ± is plus.
a=-\frac{\sqrt{106}}{2}
Now solve the equation a=\frac{0±\frac{\sqrt{106}}{7}}{\frac{2}{7}} when ± is minus.
a=\frac{\sqrt{106}}{2} a=-\frac{\sqrt{106}}{2}
The equation is now solved.