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\left(x-2\right)\left(x+1\right)-\left(x+2\right)\left(2x+1\right)=0
Variable x cannot be equal to any of the values -2,2 since division by zero is not defined. Multiply both sides of the equation by \left(x-2\right)\left(x+2\right), the least common multiple of x+2,x-2.
x^{2}-x-2-\left(x+2\right)\left(2x+1\right)=0
Use the distributive property to multiply x-2 by x+1 and combine like terms.
x^{2}-x-2-\left(2x^{2}+5x+2\right)=0
Use the distributive property to multiply x+2 by 2x+1 and combine like terms.
x^{2}-x-2-2x^{2}-5x-2=0
To find the opposite of 2x^{2}+5x+2, find the opposite of each term.
-x^{2}-x-2-5x-2=0
Combine x^{2} and -2x^{2} to get -x^{2}.
-x^{2}-6x-2-2=0
Combine -x and -5x to get -6x.
-x^{2}-6x-4=0
Subtract 2 from -2 to get -4.
x=\frac{-\left(-6\right)±\sqrt{\left(-6\right)^{2}-4\left(-1\right)\left(-4\right)}}{2\left(-1\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -1 for a, -6 for b, and -4 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-\left(-6\right)±\sqrt{36-4\left(-1\right)\left(-4\right)}}{2\left(-1\right)}
Square -6.
x=\frac{-\left(-6\right)±\sqrt{36+4\left(-4\right)}}{2\left(-1\right)}
Multiply -4 times -1.
x=\frac{-\left(-6\right)±\sqrt{36-16}}{2\left(-1\right)}
Multiply 4 times -4.
x=\frac{-\left(-6\right)±\sqrt{20}}{2\left(-1\right)}
Add 36 to -16.
x=\frac{-\left(-6\right)±2\sqrt{5}}{2\left(-1\right)}
Take the square root of 20.
x=\frac{6±2\sqrt{5}}{2\left(-1\right)}
The opposite of -6 is 6.
x=\frac{6±2\sqrt{5}}{-2}
Multiply 2 times -1.
x=\frac{2\sqrt{5}+6}{-2}
Now solve the equation x=\frac{6±2\sqrt{5}}{-2} when ± is plus. Add 6 to 2\sqrt{5}.
x=-\left(\sqrt{5}+3\right)
Divide 6+2\sqrt{5} by -2.
x=\frac{6-2\sqrt{5}}{-2}
Now solve the equation x=\frac{6±2\sqrt{5}}{-2} when ± is minus. Subtract 2\sqrt{5} from 6.
x=\sqrt{5}-3
Divide 6-2\sqrt{5} by -2.
x=-\left(\sqrt{5}+3\right) x=\sqrt{5}-3
The equation is now solved.
\left(x-2\right)\left(x+1\right)-\left(x+2\right)\left(2x+1\right)=0
Variable x cannot be equal to any of the values -2,2 since division by zero is not defined. Multiply both sides of the equation by \left(x-2\right)\left(x+2\right), the least common multiple of x+2,x-2.
x^{2}-x-2-\left(x+2\right)\left(2x+1\right)=0
Use the distributive property to multiply x-2 by x+1 and combine like terms.
x^{2}-x-2-\left(2x^{2}+5x+2\right)=0
Use the distributive property to multiply x+2 by 2x+1 and combine like terms.
x^{2}-x-2-2x^{2}-5x-2=0
To find the opposite of 2x^{2}+5x+2, find the opposite of each term.
-x^{2}-x-2-5x-2=0
Combine x^{2} and -2x^{2} to get -x^{2}.
-x^{2}-6x-2-2=0
Combine -x and -5x to get -6x.
-x^{2}-6x-4=0
Subtract 2 from -2 to get -4.
-x^{2}-6x=4
Add 4 to both sides. Anything plus zero gives itself.
\frac{-x^{2}-6x}{-1}=\frac{4}{-1}
Divide both sides by -1.
x^{2}+\left(-\frac{6}{-1}\right)x=\frac{4}{-1}
Dividing by -1 undoes the multiplication by -1.
x^{2}+6x=\frac{4}{-1}
Divide -6 by -1.
x^{2}+6x=-4
Divide 4 by -1.
x^{2}+6x+3^{2}=-4+3^{2}
Divide 6, the coefficient of the x term, by 2 to get 3. Then add the square of 3 to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}+6x+9=-4+9
Square 3.
x^{2}+6x+9=5
Add -4 to 9.
\left(x+3\right)^{2}=5
Factor x^{2}+6x+9. 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+3\right)^{2}}=\sqrt{5}
Take the square root of both sides of the equation.
x+3=\sqrt{5} x+3=-\sqrt{5}
Simplify.
x=\sqrt{5}-3 x=-\sqrt{5}-3
Subtract 3 from both sides of the equation.