Power of a Complex Number...4

[nycmathguy]

Section 6.6

 

[MathLover1]

Apply Perfect Cube Formula: \( (a-b )^3=a^3-3a^2b+3ab^2-b^3\) where \(a=sqrt(5)\),\( b=4i\)

=\((sqrt(5))^3-3(sqrt(5)^2*4i+3sqrt(5)(4i)^2-(4i)^3\).........simplify

= \(-43sqrt(5)+4*i\)

= \(-96.151 +4* i\)

 

[nycmathguy]

Apply Perfect Cube Formula: \( (a-b )^3=a^3-3a^2b+3ab^2-b^3\) where \(a=sqrt(5)\),\( b=4i\)

=\((sqrt(5))^3-3(sqrt(5)^2*4i+3sqrt(5)(4i)^2-(4i)^3\).........simplify

= \(-43sqrt(5)+4*i\)

= \(-96.151 +4* i\)

Ron Larson does not instruct to use the Perfect Cube Formula. I need to solve it as he instructed in Section 6.6. Cool formula but he said nothing about it.