SOLUTION: find cubic polynomial with the sum, sum of the product of its zeros taken two at a time, and product of its zeros as 5, -2, -24 respectively.

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Question 1030215: find cubic polynomial with the sum, sum of the product of its zeros taken two at a time, and product of its zeros as 5, -2, -24 respectively.
Found 2 solutions by josgarithmetic, ikleyn:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Let these be the roots: p, r, v.

The description is this system:
system%28p%2Br%2Bv=5%2Cpr%2Brv%2Bpr=-2%2Cprv=-24%29

This is not a linear system, and solving it may take many steps. I have not gone further.

Answer by ikleyn(52777) About Me  (Show Source):
You can put this solution on YOUR website!
.
find cubic polynomial with the sum, sum of the product of its zeros taken two at a time, and product of its zeros as 5, -2, -24 respectively.
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Let this polynomial be 

p(x) = x%5E3+%2B+ax%5E2+%2B+bx+%2B+c = %28x-x%5B1%5D%29%2A%28x-x%5B2%5D%29%2A%28x-x%5B3%5D%29,

and x%5B1%5D, x%5B2%5D and x%5B3%5D are its roots.


Then, as you can check by performing multiplication and opening the parentheses,

a = -%28x%5B1%5D+%2B+x%5B2%5D+%2B+x%5B3%5D%29 = -5,

b = x%5B1%5D%2Ax%5B2%5D+%2B+x%5B1%5D%2Ax%5B3%5D+%2B+x%5B2%5D%2Ax%5B3%5D = -2,

c = -x%5B1%5D%2Ax%5B2%5D%2Ax%5B3%5D = 24.

So, the polynomial is p(x) = x%5E3+-+5x%5E2++-+2x+%2B+24.