Question

3x^2-28=0

Answer 1

3x^(2)-28=0

Since -28 does not contain the variable to solve for, move it to the right-hand side of the equation by adding 28 to both sides.
3x^(2)=28

Divide each term in the equation by 3.
(3x^(2))/(3)=(28)/(3)

Simplify the left-hand side of the equation by canceling the common factors.
x^(2)=(28)/(3)

Take the square root of both sides of the equation to eliminate the exponent on the left-hand side.
x=+-sqrt((28)/(3))

Pull all perfect square roots out from under the radical. In this case, remove the 2 because it is a perfect square.
x=+-2sqrt((7)/(3))
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First, substitute in the + portion of the +- to find the first solution.
x=2sqrt((7)/(3))

Next, substitute in the - portion of the +- to find the second solution.
x=-2sqrt((7)/(3))

The complete solution is the result of both the + and - portions of the solution.
x=2sqrt((7)/(3)),-2sqrt((7)/(3))
x=3.055,-3.055