Is this correct please - Binomial Theorem

[Natasha1]

I'm a complete beginner at these:

(3n+1)^3 = (3n)^3 + 3(3n)^2 + 3(3n)^2 + 1

which would give me

= 3 (9n^3 + 6n^2) +1 is this correct?

 

[Natasha1]

anyone ??

 

[0rthodontist]

No, that is not correct.

(3n)^3 + 3(3n)^2 + 3(3n)^2 + 1

Your exponents should go from 3 down to 0.

3 (9n^3 + 6n^2) +1

This is also not correct.

 

[HallsofIvy]

I'm a complete beginner at these:

(3n+1)^3 = (3n)^3 + 3(3n)^2 + 3(3n)^2 + 1

Perhaps it is a typo but you should not have "^2" twice.

which would give me

= 3 (9n^3 + 6n^2) +1 is this correct?

You have added 3(3n)^2 and 3(2n)^2 but the second shouldn't be squared.

 

[Natasha1]

thanks :-)