How do you solve x4 3x2 minus 28 equals 0?

Answer 1

one way is to let x^2=m, then you have an equation m^2+3m-28=0, and then you solve this quadratic equation for m, and you get:

m=4, or m=-7... since m represents x^2, m can only be positive (if we are dealing with real numbers), so m=-7 is not possible solution...

now if m=4, the x^2=4, and solving this equation: x=2 or x=-2