SOLUTION: Identify the degree of the polynomial. Find all zeros (real and imaginary) and indicate their multiplicity if greater than 1. {{{P(x)=(x - 8)^3(x^2 +49)(4x^2 - 12x - 1)}}}

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Question 1156238: Identify the degree of the polynomial. Find all zeros (real and imaginary) and indicate their multiplicity if greater than 1.

Answer by Edwin McCravy(20060)   (Show Source): You can put this solution on YOUR website!
There is no need to multiply that out, collect terms and write in descending
order.  But I went ahead and did it anyway, and got:



So we see that the degree is 7, the largest exponent of x.

However, we could have told that by observing that the factor (x-8)³ would
contribute a term in x³, the factor (x²+49) would contribute a term in x²
and the factor (4x²-12x-1) would contribute a term in x², so we add the
powers 3+2+2=7 and know that the degree is 7 without multiplying it out.

To find all the zeros, we set the right side of P(x) equal to zero and use the
zero-factor property:

 



(x-8)³ = 0; x²+49 = 0;   4x²-12x-1 = 0
   x-8 = 0;    x² = 49;
     x = 8;     x = ±7i;

The 8 has multiplicity 3.
That's because if we wrote 
(x-8)³ 
as
(x-8)(x-8)(x-8) = 0
we would have
x-8=0; x-8=0; x-8=0
  x=8;   x=8;   x=8

and 8 would be a zero three times.

The last one won't factor, so we use the quadratic formula










So the zeros are

8 with multiplicity 3
7i with multiplicity 1
-7i with multiplicity 1

with multiplicity 1
and

with multiplicity 1

Edwin

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