Solve.
-$x ^ { 4 } - 20 x ^ { 2 } - 576 = 0$
A) $\{ - 6,6 , - 4,4 \}$
B) $\{ - 6,6 , - 4 i , 4 i \}$
C) $\{ - 36,36 , - 16 i , 16 i \}$
D) $\{ - 4,4 , - 6 \mathrm { i } , 6 \mathrm { i } \}$

Question

Quizplus · Accepted Answer

This equation can be solved by substituting $y = x^2$, turning it into a quadratic equation $y^2 - 20y - 576 = 0$. Solving this quadratic equation gives $y = 36$ and $y = -16$. Substituting back $x^2 = y$, for $y = 36$ we get $x = 6$ and $x = -6$, and for $y = -16$ we get $x = 4i$ and $x = -4i$, where $i$ is the imaginary unit.

Solve - x4−20x2−576=0x ^ { 4 } - 20 x ^ { 2 } - 576 = 0x4−20x2−576=0

Solve
- $x ^ { 4 } - 20 x ^ { 2 } - 576 = 0$