Solve =-3x^2-8x-3

$$= - 3 x ^ { 2 } - 8 x - 3$$

Factor

$$-3\left(x-\frac{-\sqrt{7}-4}{3}\right)\left(x-\frac{\sqrt{7}-4}{3}\right)$$

Steps Using the Quadratic Formula

Quadratic polynomial can be factored using the transformation ax^{2}+bx+c=a\left(x-x_{1}\right)\left(x-x_{2}\right), where x_{1} and x_{2} are the solutions of the quadratic equation ax^{2}+bx+c=0.

$$-3x^{2}-8x-3=0$$

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.

$$x=\frac{-\left(-8\right)±\sqrt{\left(-8\right)^{2}-4\left(-3\right)\left(-3\right)}}{2\left(-3\right)}$$

Square -8.

$$x=\frac{-\left(-8\right)±\sqrt{64-4\left(-3\right)\left(-3\right)}}{2\left(-3\right)}$$

Multiply -4 times -3.

$$x=\frac{-\left(-8\right)±\sqrt{64+12\left(-3\right)}}{2\left(-3\right)}$$

Multiply 12 times -3.

$$x=\frac{-\left(-8\right)±\sqrt{64-36}}{2\left(-3\right)}$$

Add 64 to -36.

$$x=\frac{-\left(-8\right)±\sqrt{28}}{2\left(-3\right)}$$

Take the square root of 28.

$$x=\frac{-\left(-8\right)±2\sqrt{7}}{2\left(-3\right)}$$

The opposite of -8 is 8.

$$x=\frac{8±2\sqrt{7}}{2\left(-3\right)}$$

Multiply 2 times -3.

$$x=\frac{8±2\sqrt{7}}{-6}$$

Now solve the equation x=\frac{8±2\sqrt{7}}{-6} when ± is plus. Add 8 to 2\sqrt{7}.

$$x=\frac{2\sqrt{7}+8}{-6}$$

Divide 8+2\sqrt{7} by -6.

$$x=\frac{-\sqrt{7}-4}{3}$$

Now solve the equation x=\frac{8±2\sqrt{7}}{-6} when ± is minus. Subtract 2\sqrt{7} from 8.

$$x=\frac{8-2\sqrt{7}}{-6}$$

Divide 8-2\sqrt{7} by -6.

$$x=\frac{\sqrt{7}-4}{3}$$

Factor the original expression using ax^{2}+bx+c=a\left(x-x_{1}\right)\left(x-x_{2}\right). Substitute \frac{-4-\sqrt{7}}{3} for x_{1} and \frac{-4+\sqrt{7}}{3} for x_{2}.

$$-3x^{2}-8x-3=-3\left(x-\frac{-\sqrt{7}-4}{3}\right)\left(x-\frac{\sqrt{7}-4}{3}\right)$$

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.

$$x ^ 2 +\frac{8}{3}x +1 = 0$$

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

$$r + s = -\frac{8}{3} rs = 1$$

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 = 1

$$(-\frac{4}{3} - u) (-\frac{4}{3} + u) = 1$$

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

$$\frac{16}{9} - u^2 = 1$$

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

$$-u^2 = 1-\frac{16}{9} = -\frac{7}{9}$$

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

$$u^2 = \frac{7}{9} u = \pm\sqrt{\frac{7}{9}} = \pm \frac{\sqrt{7}}{3}$$

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

$$r =-\frac{4}{3} - \frac{\sqrt{7}}{3} = -2.215 s = -\frac{4}{3} + \frac{\sqrt{7}}{3} = -0.451$$

Evaluate

$$-3x^{2}-8x-3$$