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x+3-xx=x\times 4+2x-3
Variable x cannot be equal to 0 since division by zero is not defined. Multiply both sides of the equation by x.
x+3-x^{2}=x\times 4+2x-3
Multiply x and x to get x^{2}.
x+3-x^{2}=6x-3
Combine x\times 4 and 2x to get 6x.
x+3-x^{2}-6x=-3
Subtract 6x from both sides.
-5x+3-x^{2}=-3
Combine x and -6x to get -5x.
-5x+3-x^{2}+3=0
Add 3 to both sides.
-5x+6-x^{2}=0
Add 3 and 3 to get 6.
-x^{2}-5x+6=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{-\left(-5\right)±\sqrt{\left(-5\right)^{2}-4\left(-1\right)\times 6}}{2\left(-1\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -1 for a, -5 for b, and 6 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-\left(-5\right)±\sqrt{25-4\left(-1\right)\times 6}}{2\left(-1\right)}
Square -5.
x=\frac{-\left(-5\right)±\sqrt{25+4\times 6}}{2\left(-1\right)}
Multiply -4 times -1.
x=\frac{-\left(-5\right)±\sqrt{25+24}}{2\left(-1\right)}
Multiply 4 times 6.
x=\frac{-\left(-5\right)±\sqrt{49}}{2\left(-1\right)}
Add 25 to 24.
x=\frac{-\left(-5\right)±7}{2\left(-1\right)}
Take the square root of 49.
x=\frac{5±7}{2\left(-1\right)}
The opposite of -5 is 5.
x=\frac{5±7}{-2}
Multiply 2 times -1.
x=\frac{12}{-2}
Now solve the equation x=\frac{5±7}{-2} when ± is plus. Add 5 to 7.
x=-6
Divide 12 by -2.
x=-\frac{2}{-2}
Now solve the equation x=\frac{5±7}{-2} when ± is minus. Subtract 7 from 5.
x=1
Divide -2 by -2.
x=-6 x=1
The equation is now solved.
x+3-xx=x\times 4+2x-3
Variable x cannot be equal to 0 since division by zero is not defined. Multiply both sides of the equation by x.
x+3-x^{2}=x\times 4+2x-3
Multiply x and x to get x^{2}.
x+3-x^{2}=6x-3
Combine x\times 4 and 2x to get 6x.
x+3-x^{2}-6x=-3
Subtract 6x from both sides.
-5x+3-x^{2}=-3
Combine x and -6x to get -5x.
-5x-x^{2}=-3-3
Subtract 3 from both sides.
-5x-x^{2}=-6
Subtract 3 from -3 to get -6.
-x^{2}-5x=-6
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}-5x}{-1}=-\frac{6}{-1}
Divide both sides by -1.
x^{2}+\left(-\frac{5}{-1}\right)x=-\frac{6}{-1}
Dividing by -1 undoes the multiplication by -1.
x^{2}+5x=-\frac{6}{-1}
Divide -5 by -1.
x^{2}+5x=6
Divide -6 by -1.
x^{2}+5x+\left(\frac{5}{2}\right)^{2}=6+\left(\frac{5}{2}\right)^{2}
Divide 5, the coefficient of the x term, by 2 to get \frac{5}{2}. Then add the square of \frac{5}{2} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}+5x+\frac{25}{4}=6+\frac{25}{4}
Square \frac{5}{2} by squaring both the numerator and the denominator of the fraction.
x^{2}+5x+\frac{25}{4}=\frac{49}{4}
Add 6 to \frac{25}{4}.
\left(x+\frac{5}{2}\right)^{2}=\frac{49}{4}
Factor x^{2}+5x+\frac{25}{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{5}{2}\right)^{2}}=\sqrt{\frac{49}{4}}
Take the square root of both sides of the equation.
x+\frac{5}{2}=\frac{7}{2} x+\frac{5}{2}=-\frac{7}{2}
Simplify.
x=1 x=-6
Subtract \frac{5}{2} from both sides of the equation.