Solve.
-$x ^ { 4 } - 22 x ^ { 2 } - 75 = 0$
A) $5 , i \sqrt { 3 }$
B) $- 5,5 , - \mathrm { i } \sqrt { 3 } , \mathrm { i } \sqrt { 3 }$
C) $- \sqrt { 3 } , \sqrt { 3 } , - 5 i , 5 i$,
D) $- 25,3$

Question

Quizplus · Accepted Answer

This equation can be solved by substituting $y = x^2$, turning it into a quadratic equation $y^2 - 22y - 75 = 0$. Solving this gives $y = 25$ and $y = -3$. Substituting back $x^2 = 25$ gives $x = 5$ and $x = -5$, and $x^2 = -3$ gives $x = i\sqrt{3}$ and $x = -i\sqrt{3}$.

Solve - x4−22x2−75=0x ^ { 4 } - 22 x ^ { 2 } - 75 = 0x4−22x2−75=0

Solve
- $x ^ { 4 } - 22 x ^ { 2 } - 75 = 0$