Solve -2x^2-10x-8>0

$$-2 { x }^{ 2 } -10x-8 > 0$$

Solve for x

$$x\in \left(-4,-1\right)$$

Steps Using the Quadratic Formula

Multiply the inequality by -1 to make the coefficient of the highest power in -2x^{2}-10x-8 positive. Since -1 is negative, the inequality direction is changed.

$$2x^{2}+10x+8<0$$

To solve the inequality, factor the left hand side. 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.

$$2x^{2}+10x+8=0$$

All equations of the form ax^{2}+bx+c=0 can be solved using the quadratic formula: \frac{-b±\sqrt{b^{2}-4ac}}{2a}. Substitute 2 for a, 10 for b, and 8 for c in the quadratic formula.

$$x=\frac{-10±\sqrt{10^{2}-4\times 2\times 8}}{2\times 2}$$

Do the calculations.

$$x=\frac{-10±6}{4}$$

Solve the equation x=\frac{-10±6}{4} when ± is plus and when ± is minus.

$$x=-1 x=-4$$

Rewrite the inequality by using the obtained solutions.

$$2\left(x+1\right)\left(x+4\right)<0$$

For the product to be negative, x+1 and x+4 have to be of the opposite signs. Consider the case when x+1 is positive and x+4 is negative.

$$x+1>0 x+4<0$$

This is false for any x.

$$x\in \emptyset$$

Consider the case when x+4 is positive and x+1 is negative.

$$x+4>0 x+1<0$$

The solution satisfying both inequalities is x\in \left(-4,-1\right).

$$x\in \left(-4,-1\right)$$

The final solution is the union of the obtained solutions.

$$x\in \left(-4,-1\right)$$