Question

State how many imaginary and real zeros the function has.

f(x) = x4 - 15x2 - 16

Answer 1

solve \(u^2-15u-16=0\) and then replace \(u\) by \(x^2\)

Answer 2

this one factors easily, so you should be in good shape

Answer 3

but how do i know how many are real and imiginary

Answer 4

That's why you need to solve it to find out!

Answer 5

there are 2 imaginary right? and 2 real?

Answer 6

Descartes' rule of signs probably won't hep here, huh?

Answer 7

@CliffSedge no

Answer 8

did you factor? i get
\[(u+1)(u-16)=0\] so
\[(x^2+1)(x^2-16)=0\]

Answer 9

thast what i got too

Answer 10

that means \(x^2=-1\) two complex zeros, namely \(i, -i\)

Answer 11

ok thank you!!!!