## anonymous one year ago If f(x) = x3 – 2x2, which expression is equivalent to f(i)?

1. anonymous

–2 + i –2 – i 2 + i 2 – I My choices

2. amoodarya

$i=\sqrt{-1}\\i^2=-1\\i^3=i^2i=-i\\i^4=(i^2)^2=(-1)^2=1\\$

3. amoodarya

$f(i)=i^3-2i^2=\\i^2i-2(-1)$

4. amoodarya

can you go on ?

5. anonymous

No, I honestly don't understand this section on complex number I've been working on the same quiz since 8:00

6. amoodarya

you can replace i^3 by -i and i^2=-1 put in function let me see your work

7. amoodarya

where are you ?