Solve for x (complex solution)
x=-i
x=i
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-2x^{2}=-2+4
Add 4 to both sides.
-2x^{2}=2
Add -2 and 4 to get 2.
x^{2}=\frac{2}{-2}
Divide both sides by -2.
x^{2}=-1
Divide 2 by -2 to get -1.
x=i x=-i
The equation is now solved.
-4-2x^{2}+2=0
Add 2 to both sides.
-2-2x^{2}=0
Add -4 and 2 to get -2.
-2x^{2}-2=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.
x=\frac{0±\sqrt{0^{2}-4\left(-2\right)\left(-2\right)}}{2\left(-2\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -2 for a, 0 for b, and -2 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{0±\sqrt{-4\left(-2\right)\left(-2\right)}}{2\left(-2\right)}
Square 0.
x=\frac{0±\sqrt{8\left(-2\right)}}{2\left(-2\right)}
Multiply -4 times -2.
x=\frac{0±\sqrt{-16}}{2\left(-2\right)}
Multiply 8 times -2.
x=\frac{0±4i}{2\left(-2\right)}
Take the square root of -16.
x=\frac{0±4i}{-4}
Multiply 2 times -2.
x=-i
Now solve the equation x=\frac{0±4i}{-4} when ± is plus.
x=i
Now solve the equation x=\frac{0±4i}{-4} when ± is minus.
x=-i x=i
The equation is now solved.
Examples
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{ x } ^ { 2 } - 4 x - 5 = 0
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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}