The expression 81 p^4 + 108p^3r^3 + 54p^2r^6 + 12pr^9 + r^12 is the expansion of which binomial?
My answer: (3p + r^3)^4
2 answers
yes
coefs of row 4
1 4 6 4 1
so
a^4 + 4 a^3 b + 6 a^2 b^2 + 4 a b^3 + b^4
(3p+r^3)^4
a = 3p
b = r^3
a^4 = 81 p^4 check
4 a^3 b = 4*27 or 108 p^3 r^3 check
6 a^2 b^2 = 6*9 or 54 p^2 r^6 check
etc
1 4 6 4 1
so
a^4 + 4 a^3 b + 6 a^2 b^2 + 4 a b^3 + b^4
(3p+r^3)^4
a = 3p
b = r^3
a^4 = 81 p^4 check
4 a^3 b = 4*27 or 108 p^3 r^3 check
6 a^2 b^2 = 6*9 or 54 p^2 r^6 check
etc
1 answer