Solve.
-$x ^ { 4 } - 5 x ^ { 2 } - 36 = 0$
A) $- 9,9 , - 4 i , 4 i$
B) $- 3,3 , - 2 \mathrm { i } , 2 \mathrm { i }$
C) $- 2,2 , - 3 i , 3 i$
D) $- 3,3 , - 2,2$

Question

Quizplus · Accepted Answer

This equation can be solved by substituting $y = x^2$, turning it into a quadratic equation $y^2 - 5y - 36 = 0$. Solving this quadratic equation gives $y = 9$ and $y = -4$. Substituting back $x^2 = y$, we get $x^2 = 9$ which gives $x = 3$ and $x = -3$, and $x^2 = -4$ which gives $x = 2i$ and $x = -2i$.

Solve - x4−5x2−36=0x ^ { 4 } - 5 x ^ { 2 } - 36 = 0x4−5x2−36=0

Solve
- $x ^ { 4 } - 5 x ^ { 2 } - 36 = 0$