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2\left(2x+9\right)-\left(x-3\right)x=0
Variable x cannot be equal to 3 since division by zero is not defined. Multiply both sides of the equation by 2\left(x-3\right)^{2}, the least common multiple of x^{2}-6x+9,2x-6.
4x+18-\left(x-3\right)x=0
Use the distributive property to multiply 2 by 2x+9.
4x+18-\left(x^{2}-3x\right)=0
Use the distributive property to multiply x-3 by x.
4x+18-x^{2}+3x=0
To find the opposite of x^{2}-3x, find the opposite of each term.
7x+18-x^{2}=0
Combine 4x and 3x to get 7x.
-x^{2}+7x+18=0
Rearrange the polynomial to put it in standard form. Place the terms in order from highest to lowest power.
a+b=7 ab=-18=-18
To solve the equation, factor the left hand side by grouping. First, left hand side needs to be rewritten as -x^{2}+ax+bx+18. To find a and b, set up a system to be solved.
-1,18 -2,9 -3,6
Since ab is negative, a and b have the opposite signs. Since a+b is positive, the positive number has greater absolute value than the negative. List all such integer pairs that give product -18.
-1+18=17 -2+9=7 -3+6=3
Calculate the sum for each pair.
a=9 b=-2
The solution is the pair that gives sum 7.
\left(-x^{2}+9x\right)+\left(-2x+18\right)
Rewrite -x^{2}+7x+18 as \left(-x^{2}+9x\right)+\left(-2x+18\right).
-x\left(x-9\right)-2\left(x-9\right)
Factor out -x in the first and -2 in the second group.
\left(x-9\right)\left(-x-2\right)
Factor out common term x-9 by using distributive property.
x=9 x=-2
To find equation solutions, solve x-9=0 and -x-2=0.
2\left(2x+9\right)-\left(x-3\right)x=0
Variable x cannot be equal to 3 since division by zero is not defined. Multiply both sides of the equation by 2\left(x-3\right)^{2}, the least common multiple of x^{2}-6x+9,2x-6.
4x+18-\left(x-3\right)x=0
Use the distributive property to multiply 2 by 2x+9.
4x+18-\left(x^{2}-3x\right)=0
Use the distributive property to multiply x-3 by x.
4x+18-x^{2}+3x=0
To find the opposite of x^{2}-3x, find the opposite of each term.
7x+18-x^{2}=0
Combine 4x and 3x to get 7x.
-x^{2}+7x+18=0
All equations of the form ax^{2}+bx+c=0 can be solved using the quadratic formula: \frac{-b±\sqrt{b^{2}-4ac}}{2a}. The quadratic formula gives two solutions, one when ± is addition and one when it is subtraction.
x=\frac{-7±\sqrt{7^{2}-4\left(-1\right)\times 18}}{2\left(-1\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -1 for a, 7 for b, and 18 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-7±\sqrt{49-4\left(-1\right)\times 18}}{2\left(-1\right)}
Square 7.
x=\frac{-7±\sqrt{49+4\times 18}}{2\left(-1\right)}
Multiply -4 times -1.
x=\frac{-7±\sqrt{49+72}}{2\left(-1\right)}
Multiply 4 times 18.
x=\frac{-7±\sqrt{121}}{2\left(-1\right)}
Add 49 to 72.
x=\frac{-7±11}{2\left(-1\right)}
Take the square root of 121.
x=\frac{-7±11}{-2}
Multiply 2 times -1.
x=\frac{4}{-2}
Now solve the equation x=\frac{-7±11}{-2} when ± is plus. Add -7 to 11.
x=-2
Divide 4 by -2.
x=-\frac{18}{-2}
Now solve the equation x=\frac{-7±11}{-2} when ± is minus. Subtract 11 from -7.
x=9
Divide -18 by -2.
x=-2 x=9
The equation is now solved.
2\left(2x+9\right)-\left(x-3\right)x=0
Variable x cannot be equal to 3 since division by zero is not defined. Multiply both sides of the equation by 2\left(x-3\right)^{2}, the least common multiple of x^{2}-6x+9,2x-6.
4x+18-\left(x-3\right)x=0
Use the distributive property to multiply 2 by 2x+9.
4x+18-\left(x^{2}-3x\right)=0
Use the distributive property to multiply x-3 by x.
4x+18-x^{2}+3x=0
To find the opposite of x^{2}-3x, find the opposite of each term.
7x+18-x^{2}=0
Combine 4x and 3x to get 7x.
7x-x^{2}=-18
Subtract 18 from both sides. Anything subtracted from zero gives its negation.
-x^{2}+7x=-18
Quadratic equations such as this one can be solved by completing the square. In order to complete the square, the equation must first be in the form x^{2}+bx=c.
\frac{-x^{2}+7x}{-1}=-\frac{18}{-1}
Divide both sides by -1.
x^{2}+\frac{7}{-1}x=-\frac{18}{-1}
Dividing by -1 undoes the multiplication by -1.
x^{2}-7x=-\frac{18}{-1}
Divide 7 by -1.
x^{2}-7x=18
Divide -18 by -1.
x^{2}-7x+\left(-\frac{7}{2}\right)^{2}=18+\left(-\frac{7}{2}\right)^{2}
Divide -7, the coefficient of the x term, by 2 to get -\frac{7}{2}. Then add the square of -\frac{7}{2} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}-7x+\frac{49}{4}=18+\frac{49}{4}
Square -\frac{7}{2} by squaring both the numerator and the denominator of the fraction.
x^{2}-7x+\frac{49}{4}=\frac{121}{4}
Add 18 to \frac{49}{4}.
\left(x-\frac{7}{2}\right)^{2}=\frac{121}{4}
Factor x^{2}-7x+\frac{49}{4}. In general, when x^{2}+bx+c is a perfect square, it can always be factored as \left(x+\frac{b}{2}\right)^{2}.
\sqrt{\left(x-\frac{7}{2}\right)^{2}}=\sqrt{\frac{121}{4}}
Take the square root of both sides of the equation.
x-\frac{7}{2}=\frac{11}{2} x-\frac{7}{2}=-\frac{11}{2}
Simplify.
x=9 x=-2
Add \frac{7}{2} to both sides of the equation.