college math teacher, algebra textbook author, 3D math artist, podcaster, webmaster, and distance runner. all in different degrees of present or former-ness.
11K
karma
· Northern California
Activity41 Answers15 Edits
@dansmath
dansmath
commented
Nice proof! Slight sign error in middle: "The dot product is (u + v) Â· (u - v)"
on
Question #b2c5e
@dansmath
dansmath
commented
George - The 7th row of Pascal's Triangle is 1, 7, 21, 35, 35, 21, 7, 1. They are 35's not 37's. In any prime p-th row of Pascal's triangle, all the inner numbers are divisible by p. So it can't be 37 because that's not a multiple of 7. Now after multiplying by the powers of 2, the coefficients become 1, 14, 84, 280, 560, 672, 448, 128. - dansmath to the rescue!
on
What is the binomial expansion of #(x + 2y)^7#?