Question

how do I find all zeroes of -3x^4+27x^2+1200=0

Answer 1

divide by -3 would be a good start

Answer 2

giving \(x^4-9x^2-400=0\) then you can try to factor, or else use the quadratic formula

Answer 3

by some math teacher miracle this one actually factors as
\[(x^2-25)(x^2+16)=0\]
\[x^2=-16\] gives two complex zeros,
\[x^2=25\] gives the two obvious real ones

Answer 4

this is what I have -3(x-5)(x+5)(x^2+16)

Answer 5

'math teacher miracle' indeed!

Answer 6

do I set x-5=0 and x+5=0 but what about x^2+16=0 what would it be

Answer 7

Yes. x^2 = -16 will give two imaginary solutions.

Answer 8

=-i4

Answer 9

You'll get a positive and negative 4i.