Solve for x
x=3
x=-3
Graph
Share
Copied to clipboard
\frac{4}{9}x^{2}-4=0
Swap sides so that all variable terms are on the left hand side.
x^{2}-9=0
Divide both sides by \frac{4}{9}.
\left(x-3\right)\left(x+3\right)=0
Consider x^{2}-9. Rewrite x^{2}-9 as x^{2}-3^{2}. The difference of squares can be factored using the rule: a^{2}-b^{2}=\left(a-b\right)\left(a+b\right).
x=3 x=-3
To find equation solutions, solve x-3=0 and x+3=0.
\frac{4}{9}x^{2}-4=0
Swap sides so that all variable terms are on the left hand side.
\frac{4}{9}x^{2}=4
Add 4 to both sides. Anything plus zero gives itself.
x^{2}=4\times \frac{9}{4}
Multiply both sides by \frac{9}{4}, the reciprocal of \frac{4}{9}.
x^{2}=9
Multiply 4 and \frac{9}{4} to get 9.
x=3 x=-3
Take the square root of both sides of the equation.
\frac{4}{9}x^{2}-4=0
Swap sides so that all variable terms are on the left hand side.
x=\frac{0±\sqrt{0^{2}-4\times \frac{4}{9}\left(-4\right)}}{2\times \frac{4}{9}}
This equation is in standard form: ax^{2}+bx+c=0. Substitute \frac{4}{9} for a, 0 for b, and -4 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{0±\sqrt{-4\times \frac{4}{9}\left(-4\right)}}{2\times \frac{4}{9}}
Square 0.
x=\frac{0±\sqrt{-\frac{16}{9}\left(-4\right)}}{2\times \frac{4}{9}}
Multiply -4 times \frac{4}{9}.
x=\frac{0±\sqrt{\frac{64}{9}}}{2\times \frac{4}{9}}
Multiply -\frac{16}{9} times -4.
x=\frac{0±\frac{8}{3}}{2\times \frac{4}{9}}
Take the square root of \frac{64}{9}.
x=\frac{0±\frac{8}{3}}{\frac{8}{9}}
Multiply 2 times \frac{4}{9}.
x=3
Now solve the equation x=\frac{0±\frac{8}{3}}{\frac{8}{9}} when ± is plus.
x=-3
Now solve the equation x=\frac{0±\frac{8}{3}}{\frac{8}{9}} when ± is minus.
x=3 x=-3
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}