is the answer A??
Let P(x)=1+x+x2+x3+x4+x5
What is the remainder when P(x12) is divided by P(x)??
(A)0 (B)6 (C)1+x (D)1+x+x2+x3+x4
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6 Answers
is the answer b.
my method is that p(-1)=0
now to find the remainder of p(x12)=g(x0)
you can simply find g(-1)=6(this is because if you factorize p(x) you find that its other roots are complex which cannot contribute to the remainder of g(x0) .also you can verify by factorizing g(x0) further.)
Simply do this
P(x^{12}) =1+x^{12}+x^{24}+x^{36}+x^{48}+x^{60}
= =6+(x^{12}-1)+(x^{24}-1)+(x^{36}-1)+(x^{48}-1)+(x^{60}-1)
Each of the bracketed expressions is divisible by x^6-1 and hence by P(x)
A more general discussion can be read at http://www.goiit.com/posts/list/algebra-question-56626.htm
after prophet sir's #4 i dont think there's should be any kind of ambiguity..