Solve for x
x = \frac{\sqrt{65}}{5} \approx 1.61245155
x = -\frac{\sqrt{65}}{5} \approx -1.61245155
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5x^{2}-13=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{0±\sqrt{0^{2}-4\times 5\left(-13\right)}}{2\times 5}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 5 for a, 0 for b, and -13 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{0±\sqrt{-4\times 5\left(-13\right)}}{2\times 5}
Square 0.
x=\frac{0±\sqrt{-20\left(-13\right)}}{2\times 5}
Multiply -4 times 5.
x=\frac{0±\sqrt{260}}{2\times 5}
Multiply -20 times -13.
x=\frac{0±2\sqrt{65}}{2\times 5}
Take the square root of 260.
x=\frac{0±2\sqrt{65}}{10}
Multiply 2 times 5.
x=\frac{\sqrt{65}}{5}
Now solve the equation x=\frac{0±2\sqrt{65}}{10} when ± is plus.
x=-\frac{\sqrt{65}}{5}
Now solve the equation x=\frac{0±2\sqrt{65}}{10} when ± is minus.
x=\frac{\sqrt{65}}{5} x=-\frac{\sqrt{65}}{5}
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}