Find the expansion of (r + 4)</I>3
I have the hardest time ever with this topic. I need a good, clear explanation on how to expand these (for someone who's an apparent math moron).
Hello, BlueStar!
The very least you could do is mutliply it out . . .Find the expansion of: .$\displaystyle (r + 4)^3$
First, find $\displaystyle (r +4)^2$
. . $\displaystyle (r + 4)^2 \;=\;(r+4)^2 \;=\;r^2 + 4r +4r + 16 \;=\;r^2 + 8r + 16$
The multiply by another $\displaystyle (r+4)$
. . $\displaystyle (r+4)(r^2 + 8r + 16) \;=\;r^3 + 8r^2 + 16r + 4r^2 + 32r + 64 \;=\;\boxed{r^3 + 12r^2 + 48r + 64}$
If you are seeking a shortcut to this type of multiplication,
. . then you want the Binomial Theorem (or Binomial Expansion).
Perhaps someone will explain it to you . . . or not.