Solve for x
x = \frac{\sqrt{7} + 1}{3} \approx 1.215250437
x=\frac{1-\sqrt{7}}{3}\approx -0.54858377
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2x+4-3x^{2}=2
Subtract 3x^{2} from both sides.
2x+4-3x^{2}-2=0
Subtract 2 from both sides.
2x+2-3x^{2}=0
Subtract 2 from 4 to get 2.
-3x^{2}+2x+2=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{-2±\sqrt{2^{2}-4\left(-3\right)\times 2}}{2\left(-3\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -3 for a, 2 for b, and 2 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-2±\sqrt{4-4\left(-3\right)\times 2}}{2\left(-3\right)}
Square 2.
x=\frac{-2±\sqrt{4+12\times 2}}{2\left(-3\right)}
Multiply -4 times -3.
x=\frac{-2±\sqrt{4+24}}{2\left(-3\right)}
Multiply 12 times 2.
x=\frac{-2±\sqrt{28}}{2\left(-3\right)}
Add 4 to 24.
x=\frac{-2±2\sqrt{7}}{2\left(-3\right)}
Take the square root of 28.
x=\frac{-2±2\sqrt{7}}{-6}
Multiply 2 times -3.
x=\frac{2\sqrt{7}-2}{-6}
Now solve the equation x=\frac{-2±2\sqrt{7}}{-6} when ± is plus. Add -2 to 2\sqrt{7}.
x=\frac{1-\sqrt{7}}{3}
Divide -2+2\sqrt{7} by -6.
x=\frac{-2\sqrt{7}-2}{-6}
Now solve the equation x=\frac{-2±2\sqrt{7}}{-6} when ± is minus. Subtract 2\sqrt{7} from -2.
x=\frac{\sqrt{7}+1}{3}
Divide -2-2\sqrt{7} by -6.
x=\frac{1-\sqrt{7}}{3} x=\frac{\sqrt{7}+1}{3}
The equation is now solved.
2x+4-3x^{2}=2
Subtract 3x^{2} from both sides.
2x-3x^{2}=2-4
Subtract 4 from both sides.
2x-3x^{2}=-2
Subtract 4 from 2 to get -2.
-3x^{2}+2x=-2
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{-3x^{2}+2x}{-3}=-\frac{2}{-3}
Divide both sides by -3.
x^{2}+\frac{2}{-3}x=-\frac{2}{-3}
Dividing by -3 undoes the multiplication by -3.
x^{2}-\frac{2}{3}x=-\frac{2}{-3}
Divide 2 by -3.
x^{2}-\frac{2}{3}x=\frac{2}{3}
Divide -2 by -3.
x^{2}-\frac{2}{3}x+\left(-\frac{1}{3}\right)^{2}=\frac{2}{3}+\left(-\frac{1}{3}\right)^{2}
Divide -\frac{2}{3}, the coefficient of the x term, by 2 to get -\frac{1}{3}. Then add the square of -\frac{1}{3} to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}-\frac{2}{3}x+\frac{1}{9}=\frac{2}{3}+\frac{1}{9}
Square -\frac{1}{3} by squaring both the numerator and the denominator of the fraction.
x^{2}-\frac{2}{3}x+\frac{1}{9}=\frac{7}{9}
Add \frac{2}{3} to \frac{1}{9} by finding a common denominator and adding the numerators. Then reduce the fraction to lowest terms if possible.
\left(x-\frac{1}{3}\right)^{2}=\frac{7}{9}
Factor x^{2}-\frac{2}{3}x+\frac{1}{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-\frac{1}{3}\right)^{2}}=\sqrt{\frac{7}{9}}
Take the square root of both sides of the equation.
x-\frac{1}{3}=\frac{\sqrt{7}}{3} x-\frac{1}{3}=-\frac{\sqrt{7}}{3}
Simplify.
x=\frac{\sqrt{7}+1}{3} x=\frac{1-\sqrt{7}}{3}
Add \frac{1}{3} to both sides of the equation.
Examples
Quadratic equation
{ x } ^ { 2 } - 4 x - 5 = 0
Trigonometry
4 \sin \theta \cos \theta = 2 \sin \theta
Linear equation
y = 3x + 4
Arithmetic
699 * 533
Matrix
\left[ \begin{array} { l l } { 2 } & { 3 } \\ { 5 } & { 4 } \end{array} \right] \left[ \begin{array} { l l l } { 2 } & { 0 } & { 3 } \\ { -1 } & { 1 } & { 5 } \end{array} \right]
Simultaneous equation
\left. \begin{cases} { 8x+2y = 46 } \\ { 7x+3y = 47 } \end{cases} \right.
Differentiation
\frac { d } { d x } \frac { ( 3 x ^ { 2 } - 2 ) } { ( x - 5 ) }
Integration
\int _ { 0 } ^ { 1 } x e ^ { - x ^ { 2 } } d x
Limits
\lim _{x \rightarrow-3} \frac{x^{2}-9}{x^{2}+2 x-3}