Skip to main content
Solve for x
Tick mark Image
Graph

Similar Problems from Web Search

Share

28-x^{2}=0
Add 24 and 4 to get 28.
-x^{2}=-28
Subtract 28 from both sides. Anything subtracted from zero gives its negation.
x^{2}=\frac{-28}{-1}
Divide both sides by -1.
x^{2}=28
Fraction \frac{-28}{-1} can be simplified to 28 by removing the negative sign from both the numerator and the denominator.
x=2\sqrt{7} x=-2\sqrt{7}
Take the square root of both sides of the equation.
28-x^{2}=0
Add 24 and 4 to get 28.
-x^{2}+28=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\left(-1\right)\times 28}}{2\left(-1\right)}
This equation is in standard form: ax^{2}+bx+c=0. Substitute -1 for a, 0 for b, and 28 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.
x=\frac{0±\sqrt{-4\left(-1\right)\times 28}}{2\left(-1\right)}
Square 0.
x=\frac{0±\sqrt{4\times 28}}{2\left(-1\right)}
Multiply -4 times -1.
x=\frac{0±\sqrt{112}}{2\left(-1\right)}
Multiply 4 times 28.
x=\frac{0±4\sqrt{7}}{2\left(-1\right)}
Take the square root of 112.
x=\frac{0±4\sqrt{7}}{-2}
Multiply 2 times -1.
x=-2\sqrt{7}
Now solve the equation x=\frac{0±4\sqrt{7}}{-2} when ± is plus.
x=2\sqrt{7}
Now solve the equation x=\frac{0±4\sqrt{7}}{-2} when ± is minus.
x=-2\sqrt{7} x=2\sqrt{7}
The equation is now solved.