Solve for x
x=2
x=6
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\frac{1}{4}x^{2}-2x+3=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(-2\right)±\sqrt{\left(-2\right)^{2}-4\times \frac{1}{4}\times 3}}{2\times \frac{1}{4}}
This equation is in standard form: ax^{2}+bx+c=0. Substitute \frac{1}{4} for a, -2 for b, and 3 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{-\left(-2\right)±\sqrt{4-4\times \frac{1}{4}\times 3}}{2\times \frac{1}{4}}
Square -2.
x=\frac{-\left(-2\right)±\sqrt{4-3}}{2\times \frac{1}{4}}
Multiply -4 times \frac{1}{4}.
x=\frac{-\left(-2\right)±\sqrt{1}}{2\times \frac{1}{4}}
Add 4 to -3.
x=\frac{-\left(-2\right)±1}{2\times \frac{1}{4}}
Take the square root of 1.
x=\frac{2±1}{2\times \frac{1}{4}}
The opposite of -2 is 2.
x=\frac{2±1}{\frac{1}{2}}
Multiply 2 times \frac{1}{4}.
x=\frac{3}{\frac{1}{2}}
Now solve the equation x=\frac{2±1}{\frac{1}{2}} when ± is plus. Add 2 to 1.
x=6
Divide 3 by \frac{1}{2} by multiplying 3 by the reciprocal of \frac{1}{2}.
x=\frac{1}{\frac{1}{2}}
Now solve the equation x=\frac{2±1}{\frac{1}{2}} when ± is minus. Subtract 1 from 2.
x=2
Divide 1 by \frac{1}{2} by multiplying 1 by the reciprocal of \frac{1}{2}.
x=6 x=2
The equation is now solved.
\frac{1}{4}x^{2}-2x+3=0
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{1}{4}x^{2}-2x+3-3=-3
Subtract 3 from both sides of the equation.
\frac{1}{4}x^{2}-2x=-3
Subtracting 3 from itself leaves 0.
\frac{\frac{1}{4}x^{2}-2x}{\frac{1}{4}}=-\frac{3}{\frac{1}{4}}
Multiply both sides by 4.
x^{2}+\left(-\frac{2}{\frac{1}{4}}\right)x=-\frac{3}{\frac{1}{4}}
Dividing by \frac{1}{4} undoes the multiplication by \frac{1}{4}.
x^{2}-8x=-\frac{3}{\frac{1}{4}}
Divide -2 by \frac{1}{4} by multiplying -2 by the reciprocal of \frac{1}{4}.
x^{2}-8x=-12
Divide -3 by \frac{1}{4} by multiplying -3 by the reciprocal of \frac{1}{4}.
x^{2}-8x+\left(-4\right)^{2}=-12+\left(-4\right)^{2}
Divide -8, the coefficient of the x term, by 2 to get -4. Then add the square of -4 to both sides of the equation. This step makes the left hand side of the equation a perfect square.
x^{2}-8x+16=-12+16
Square -4.
x^{2}-8x+16=4
Add -12 to 16.
\left(x-4\right)^{2}=4
Factor x^{2}-8x+16. 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-4\right)^{2}}=\sqrt{4}
Take the square root of both sides of the equation.
x-4=2 x-4=-2
Simplify.
x=6 x=2
Add 4 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}