Solve 99x^2+264x-254=0

$$99 x ^ { 2 } + 264 x - 254 = 0$$

Solve for x

$$x=\frac{\sqrt{4730}}{33}-\frac{4}{3}\approx 0.750757438$$

$$x=-\frac{\sqrt{4730}}{33}-\frac{4}{3}\approx -3.417424105$$

Steps Using the Quadratic Formula

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.

$$99x^{2}+264x-254=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute 99 for a, 264 for b, and -254 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{-264±\sqrt{264^{2}-4\times 99\left(-254\right)}}{2\times 99}$$

Square 264.

$$x=\frac{-264±\sqrt{69696-4\times 99\left(-254\right)}}{2\times 99}$$

Multiply -4 times 99.

$$x=\frac{-264±\sqrt{69696-396\left(-254\right)}}{2\times 99}$$

Multiply -396 times -254.

$$x=\frac{-264±\sqrt{69696+100584}}{2\times 99}$$

Add 69696 to 100584.

$$x=\frac{-264±\sqrt{170280}}{2\times 99}$$

Take the square root of 170280.

$$x=\frac{-264±6\sqrt{4730}}{2\times 99}$$

Multiply 2 times 99.

$$x=\frac{-264±6\sqrt{4730}}{198}$$

Now solve the equation x=\frac{-264±6\sqrt{4730}}{198} when ± is plus. Add -264 to 6\sqrt{4730}.

$$x=\frac{6\sqrt{4730}-264}{198}$$

Divide -264+6\sqrt{4730} by 198.

$$x=\frac{\sqrt{4730}}{33}-\frac{4}{3}$$

Now solve the equation x=\frac{-264±6\sqrt{4730}}{198} when ± is minus. Subtract 6\sqrt{4730} from -264.

$$x=\frac{-6\sqrt{4730}-264}{198}$$

Divide -264-6\sqrt{4730} by 198.

$$x=-\frac{\sqrt{4730}}{33}-\frac{4}{3}$$

The equation is now solved.

$$x=\frac{\sqrt{4730}}{33}-\frac{4}{3} x=-\frac{\sqrt{4730}}{33}-\frac{4}{3}$$

Steps for Completing the Square

Quadratic equations such as this one can be solved by completing the square. In order to complete the square, the equation must first be in the form x^{2}+bx=c.

$$99x^{2}+264x-254=0$$

Add 254 to both sides of the equation.

$$99x^{2}+264x-254-\left(-254\right)=-\left(-254\right)$$

Subtracting -254 from itself leaves 0.

$$99x^{2}+264x=-\left(-254\right)$$

Subtract -254 from 0.

$$99x^{2}+264x=254$$

Divide both sides by 99.

$$\frac{99x^{2}+264x}{99}=\frac{254}{99}$$

Dividing by 99 undoes the multiplication by 99.

$$x^{2}+\frac{264}{99}x=\frac{254}{99}$$

Reduce the fraction \frac{264}{99} to lowest terms by extracting and canceling out 33.

$$x^{2}+\frac{8}{3}x=\frac{254}{99}$$

Divide \frac{8}{3}, the coefficient of the x term, by 2 to get \frac{4}{3}. Then add the square of \frac{4}{3} to both sides of the equation. This step makes the left hand side of the equation a perfect square.

$$x^{2}+\frac{8}{3}x+\left(\frac{4}{3}\right)^{2}=\frac{254}{99}+\left(\frac{4}{3}\right)^{2}$$

Square \frac{4}{3} by squaring both the numerator and the denominator of the fraction.

$$x^{2}+\frac{8}{3}x+\frac{16}{9}=\frac{254}{99}+\frac{16}{9}$$

Add \frac{254}{99} to \frac{16}{9} by finding a common denominator and adding the numerators. Then reduce the fraction to lowest terms if possible.

$$x^{2}+\frac{8}{3}x+\frac{16}{9}=\frac{430}{99}$$

Factor x^{2}+\frac{8}{3}x+\frac{16}{9}. In general, when x^{2}+bx+c is a perfect square, it can always be factored as \left(x+\frac{b}{2}\right)^{2}.

$$\left(x+\frac{4}{3}\right)^{2}=\frac{430}{99}$$

Take the square root of both sides of the equation.

$$\sqrt{\left(x+\frac{4}{3}\right)^{2}}=\sqrt{\frac{430}{99}}$$

Simplify.

$$x+\frac{4}{3}=\frac{\sqrt{4730}}{33} x+\frac{4}{3}=-\frac{\sqrt{4730}}{33}$$

Subtract \frac{4}{3} from both sides of the equation.

$$x=\frac{\sqrt{4730}}{33}-\frac{4}{3} x=-\frac{\sqrt{4730}}{33}-\frac{4}{3}$$

Steps Using Direct Factoring Method

Quadratic equations such as this one can be solved by a new direct factoring method that does not require guess work. To use the direct factoring method, the equation must be in the form x^2+Bx+C=0.This is achieved by dividing both sides of the equation by 99

$$x ^ 2 +\frac{8}{3}x -\frac{254}{99} = 0$$

Let r and s be the factors for the quadratic equation such that x^2+Bx+C=(x−r)(x−s) where sum of factors (r+s)=−B and the product of factors rs = C

$$r + s = -\frac{8}{3} rs = -\frac{254}{99}$$

Two numbers r and s sum up to -\frac{8}{3} exactly when the average of the two numbers is \frac{1}{2}*-\frac{8}{3} = -\frac{4}{3}. You can also see that the midpoint of r and s corresponds to the axis of symmetry of the parabola represented by the quadratic equation y=x^2+Bx+C. The values of r and s are equidistant from the center by an unknown quantity u. Express r and s with respect to variable u. <div style='padding: 8px'><img src='https://opalmath.azureedge.net/customsolver/quadraticgraph.png' style='width: 100%;max-width: 700px' /></div>

$$r = -\frac{4}{3} - u s = -\frac{4}{3} + u$$

To solve for unknown quantity u, substitute these in the product equation rs = -\frac{254}{99}

$$(-\frac{4}{3} - u) (-\frac{4}{3} + u) = -\frac{254}{99}$$

Simplify by expanding (a -b) (a + b) = a^2 – b^2

$$\frac{16}{9} - u^2 = -\frac{254}{99}$$

Simplify the expression by subtracting \frac{16}{9} on both sides

$$-u^2 = -\frac{254}{99}-\frac{16}{9} = -\frac{430}{99}$$

Simplify the expression by multiplying -1 on both sides and take the square root to obtain the value of unknown variable u

$$u^2 = \frac{430}{99} u = \pm\sqrt{\frac{430}{99}} = \pm \frac{\sqrt{430}}{\sqrt{99}}$$

The factors r and s are the solutions to the quadratic equation. Substitute the value of u to compute the r and s.

$$r =-\frac{4}{3} - \frac{\sqrt{430}}{\sqrt{99}} = -3.417 s = -\frac{4}{3} + \frac{\sqrt{430}}{\sqrt{99}} = 0.751$$