Quick Help with Maths Q

Wats_in_a_name

Not sure if this is the right place to post but This one sum has been doing my head in now for a good 45 minutes.I know it but I don't if that makes sense?!

p { margin-bottom: 0.21cm; } Explain why i[FONT=Times New Roman, serif]³[/FONT][FONT=Times New Roman, serif] = -1. If [/FONT][FONT=Times New Roman, serif]w [/FONT][FONT=Times New Roman, serif]= 3[/FONT][FONT=Times New Roman, serif]i[/FONT][FONT=Times New Roman, serif], show that [/FONT][FONT=Times New Roman, serif]w[/FONT][FONT=Times New Roman, serif]³ –[/FONT][FONT=Times New Roman, serif] [/FONT][FONT=Times New Roman, serif]w² [/FONT][FONT=Times New Roman, serif]+ 9[/FONT][FONT=Times New Roman, serif]w[/FONT][FONT=Times New Roman, serif] – 9 = 0[/FONT]

sparagon

Ok well i= root minus one..so i sqaured is minus one
And for the other just sub in w and multiply it out replacing i squared with minus one

EuropeanSon

i^3 isn't -1, it's -i.

sparagon

I never said it was.

EuropeanSon

sparagon wrote: »

I never said it was.

That was directed at the OP.

Wats_in_a_name

Turns out it was a mistake in the book. Should of read i³ = -i

So I have that one sorted but now I'm stuck on.

If x² = 9 Verify x = ± 3

Could you just go
-3 x -3 = 9
3 x 3 = 9

Then it goes on if | a + 3i | = 5 find the 2 possible values of a.

I know it's ± 4 but how do I show that?

Thanks for the help.

Wats_in_a_name

Never mind. Worked it out. I was trying to over think it!