Can someone please factor out (x + 3) cubed?

Question

jim_thompson5910 · Answer

it's already factored

jim_thompson5910 · Answer

did you mean expand?

anonymous · Answer

Perhaps I mean expand

anonymous · Answer

The other issue is expanding (x + delta x) cubed?

jim_thompson5910 · Answer

Ok first off we need to expand out (x + 3)(x + 3)

(x + 3)(x + 3) = x(x+3) + 3(x+3)

(x + 3)(x + 3) = x^2 + 3x + 3x + 9

(x + 3)(x + 3) = x^2 + 6x + 9

jim_thompson5910 · Answer

then we use this to expand out (x + 3)(x + 3)(x + 3)

jim_thompson5910 · Answer

(x + 3)^3 = (x + 3)(x + 3)(x + 3)


(x + 3)^3 = (x + 3)(x^2 + 6x + 9)


(x + 3)^3 = x(x^2 + 6x + 9) + 3(x^2 + 6x + 9)


(x + 3)^3 = x^3 + 6x^2 + 9x + 3x^2 + 18x + 27


(x + 3)^3 = x^3 + 9x^2 + 27x + 27

jim_thompson5910 · Answer

you expand (x + delta x) cubed the same way as well

anonymous · Answer

I seem to be making an algebraic error in expanding (x + delta x) cubed.  Could you please work it out for me.  Thank you so much.

jim_thompson5910 · Answer

replace delta x with another variable (say y) and try it again

anonymous · Answer

$$(a+b)³=a^3+3a²b+3ab²+b³$$ Just change a to x and b to delta x.

anonymous · Answer

Well, the problem you see is how Delta X is treated in a multiplicative relation with plain X or X squared.

jim_thompson5910 · Answer

not sure what you mean rafirank

anonymous · Answer

Jim--thank you and thank you very much to Zairhenrique.  I've got it now.  Thanks to you both.  I understand what I have been doing wrong.

jim_thompson5910 · Answer

ok glad it's making sense now

anonymous · Answer

you welcome man