Solve x^4-13x^2-48=0

$$x ^ { 4 } - 13 x ^ { 2 } - 48 = 0$$

Solve for x (complex solution)

$$x=4$$

$$x=-4$$

$$x=-\sqrt{3}i\approx -0-1.732050808i$$

$$x=\sqrt{3}i\approx 1.732050808i$$

Steps Using the Quadratic Formula

Substitute t for x^{2}.

$$t^{2}-13t-48=0$$

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 1 for a, -13 for b, and -48 for c in the quadratic formula.

$$t=\frac{-\left(-13\right)±\sqrt{\left(-13\right)^{2}-4\times 1\left(-48\right)}}{2}$$

Do the calculations.

$$t=\frac{13±19}{2}$$

Solve the equation t=\frac{13±19}{2} when ± is plus and when ± is minus.

$$t=16 t=-3$$

Since x=t^{2}, the solutions are obtained by evaluating x=±\sqrt{t} for each t.

$$x=-4 x=4 x=-\sqrt{3}i x=\sqrt{3}i$$

Solve for x

$$x=-4$$

$$x=4$$

Steps Using the Quadratic Formula

Substitute t for x^{2}.

$$t^{2}-13t-48=0$$

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 1 for a, -13 for b, and -48 for c in the quadratic formula.

$$t=\frac{-\left(-13\right)±\sqrt{\left(-13\right)^{2}-4\times 1\left(-48\right)}}{2}$$

Do the calculations.

$$t=\frac{13±19}{2}$$

Solve the equation t=\frac{13±19}{2} when ± is plus and when ± is minus.

$$t=16 t=-3$$

Since x=t^{2}, the solutions are obtained by evaluating x=±\sqrt{t} for positive t.

$$x=4 x=-4$$