SOLUTION: Solve: x^4 -3x^2 =4 (find 4 roots)
* I plugged it into my calculator and only got two root -2 and 2. There should be two more but how do you get the answers with i? (my classmat
Question 1013017: Solve: x^4 -3x^2 =4 (find 4 roots)
* I plugged it into my calculator and only got two root -2 and 2. There should be two more but how do you get the answers with i? (my classmate's answer for that are x=i and x= -i) Found 2 solutions by macston, ikleyn:Answer by macston(5194) (Show Source): You can put this solution on YOUR website! .
let y=x^2
.
x^4-3x^2=4
x^4-3x^2-4=0 Replace x^2 with y.
y^2-3y-4=0
(y-4)(y+1)=0
.
y-4=0 or y+1=0
y=4 or y=-1 . Replace y with x^2
x^2=4 . or . x^2=-1
x=+/-2 . or . x=+/-i . ( Answer by ikleyn(53938) (Show Source): You can put this solution on YOUR website! .
Solve: x^4 -3x^2 =4 (find 4 roots)
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= ,
Factor left side. You will get
= .
The roots are 2, -2, i and -i.