Solve for x (complex solution)
x=-2\sqrt{2}i\approx -0-2.828427125i
x=2\sqrt{2}i\approx 2.828427125i
Graph
Share
Copied to clipboard
\frac{1}{4}x^{2}=-2
Subtract 2 from both sides. Anything subtracted from zero gives its negation.
x^{2}=-2\times 4
Multiply both sides by 4, the reciprocal of \frac{1}{4}.
x^{2}=-8
Multiply -2 and 4 to get -8.
x=2\sqrt{2}i x=-2\sqrt{2}i
The equation is now solved.
\frac{1}{4}x^{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\times \frac{1}{4}\times 2}}{2\times \frac{1}{4}}
This equation is in standard form: ax^{2}+bx+c=0. Substitute \frac{1}{4} 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\times \frac{1}{4}\times 2}}{2\times \frac{1}{4}}
Square 0.
x=\frac{0±\sqrt{-2}}{2\times \frac{1}{4}}
Multiply -4 times \frac{1}{4}.
x=\frac{0±\sqrt{2}i}{2\times \frac{1}{4}}
Take the square root of -2.
x=\frac{0±\sqrt{2}i}{\frac{1}{2}}
Multiply 2 times \frac{1}{4}.
x=2\sqrt{2}i
Now solve the equation x=\frac{0±\sqrt{2}i}{\frac{1}{2}} when ± is plus.
x=-2\sqrt{2}i
Now solve the equation x=\frac{0±\sqrt{2}i}{\frac{1}{2}} when ± is minus.
x=2\sqrt{2}i x=-2\sqrt{2}i
The equation is now solved.
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}