SOLUTION: the degree of a polynomial p(x)is no larger than 3. we know that p(0)=3, P(-x)=p(x), and p(1/x)=p(x)/x2. find p(1)?

Algebra ->  Complex Numbers Imaginary Numbers Solvers and Lesson -> SOLUTION: the degree of a polynomial p(x)is no larger than 3. we know that p(0)=3, P(-x)=p(x), and p(1/x)=p(x)/x2. find p(1)?      Log On


   



Question 467123: the degree of a polynomial p(x)is no larger than 3. we know that p(0)=3,
P(-x)=p(x), and p(1/x)=p(x)/x2. find p(1)?

Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
Let M = x%5E2.
Then M + 461 = %28x%2B1%29%5E2.
Subtract the top equation from the bottom equation, to get
461+=+%28x%2B1%29%5E2+-+x%5E2
<==> 461+=+x%5E2+%2B+2x+%2B+1+-+x%5E2
==> 461 = 2x + 1
==> 2x = 460
==> x = 230.
Hence M = 230%5E2 = 52,900.




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We must have deg+p%28x%29+%3C=+3,
p(0) = 3, p(-x) = p(x), p%281%2Fx%29+=+p%28x%29%2Fx%5E2.
Let p%28x%29+=+ax%5E3+%2Bbx%5E2+%2B+cx+%2B+d
==> p(0) = d = 3, as given.
Now
==> a = 0 by direct correspondence of terms,
b = d, and c is some real number.
==> b = d = 3, and a = 0.
==> p%28x%29+=+3x%5E2+%2B+cx+%2B+3
Now p(x) = p(-x) ==> 3x%5E2+%2B+cx+%2B+3+=+3x%5E2+-cx+%2B+3
==> cx = -cx ==> 2cx = 0.
Since x is not zero for all values of x in the domain of p(x), this means that c = 0.
Therefore p%28x%29+=+3x%5E2+%2B+3 and p%281%29+=+3%2A1%5E2+%2B+3+=+3+%2B+3+=+6.