Solve the equation.
-$$x ^ { 4 } - 3 x ^ { 2 } - 54 = 0$$
A) $$\pm 3$$
B) $$3 , \mathrm { i } \sqrt { 6 }$$
C)-9, 6
D) $$\pm 3 , \pm i \sqrt { 6 }$$

Question

Quizplus · Accepted Answer

This equation can be solved by substituting $y = x^2$, turning it into a quadratic equation $y^2 - 3y - 54 = 0$. Solving this gives $y = 9$ and $y = -6$. Substituting back $x^2 = 9$ gives $x = \pm 3$, and $x^2 = -6$ gives $x = \pm i\sqrt{6}$.

Solve the Equation x4−3x2−54=0x ^ { 4 } - 3 x ^ { 2 } - 54 = 0x4−3x2−54=0

Solve the Equation $x ^ { 4 } - 3 x ^ { 2 } - 54 = 0$