SOLUTION: q is a degree 5 polynomial that passes through the origin, has zeros i and 7−i, and q(3)=1530. Find the equation for q.

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Question 1111319: q is a degree 5 polynomial that passes through the origin, has zeros i and 7−i, and q(3)=1530. Find the equation for q.
Answer by ikleyn(52752) About Me  (Show Source):
You can put this solution on YOUR website!
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q is a degree 5 polynomial that passes through the origin, has zeros i and 7−i, and q(3)=1530. Find the equation for q.
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First of all, your formulation is INCORRECT.

The correct formulation is THIS:

 
    q is a degree 5 polynomial with real coefficients that passes through the origin, has zeros i and 7−i, and q(3)=1530. 

    Find the equation for q.


Solution

The polynomial q(x) has x as a factor (because it "passes through the origin").


It also has the pairs of the roots i and "-i", as well as (7-i) and (7+i).


Hence, the polynomial has the form


q(x) = ax*(X-i)*(x+i)*(x-(7-i))*(x-(7+i)) = 


     = ax*(x^2+1)*((x-7)^2 +1).


where "a" is a real coefficient.


Find "a" from the condition

q(3) = 1530 = a*3*(3^2+1)*((-4)^2+1),   which is the same as

       1530 = 3a*10*17,   which implies  a = 1530%2F%283%2A10%2A17%29 = 3


Answer.  q(x) = 3x%2A%28x%5E2%2B1%29%2A%28x%5E2-14x+%2B50%29.

Solved.