Solve for x
x=9
x=-9
Graph
Share
Copied to clipboard
x^{2}-80=1
Multiply 92 and \frac{20}{23} to get 80.
x^{2}-80-1=0
Subtract 1 from both sides.
x^{2}-81=0
Subtract 1 from -80 to get -81.
\left(x-9\right)\left(x+9\right)=0
Consider x^{2}-81. Rewrite x^{2}-81 as x^{2}-9^{2}. The difference of squares can be factored using the rule: a^{2}-b^{2}=\left(a-b\right)\left(a+b\right).
x=9 x=-9
To find equation solutions, solve x-9=0 and x+9=0.
x^{2}-80=1
Multiply 92 and \frac{20}{23} to get 80.
x^{2}=1+80
Add 80 to both sides.
x^{2}=81
Add 1 and 80 to get 81.
x=9 x=-9
Take the square root of both sides of the equation.
x^{2}-80=1
Multiply 92 and \frac{20}{23} to get 80.
x^{2}-80-1=0
Subtract 1 from both sides.
x^{2}-81=0
Subtract 1 from -80 to get -81.
x=\frac{0±\sqrt{0^{2}-4\left(-81\right)}}{2}
This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 0 for b, and -81 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{0±\sqrt{-4\left(-81\right)}}{2}
Square 0.
x=\frac{0±\sqrt{324}}{2}
Multiply -4 times -81.
x=\frac{0±18}{2}
Take the square root of 324.
x=9
Now solve the equation x=\frac{0±18}{2} when ± is plus. Divide 18 by 2.
x=-9
Now solve the equation x=\frac{0±18}{2} when ± is minus. Divide -18 by 2.
x=9 x=-9
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}