Consider the polynomial P(x) = x^4 + 3x^3 + 5x^2 + 7x + 9. Let its four roots be a, b, c, d. Evaluate the expression (a + b + c)(a + b + d)(a + c + d)(b + c + d).

The roots of x^4 + 3x^3 + 5x^2 + 7x + 9 are

-1.6673 - 0.9330*i

-1.6673 + 0.9330*i

0.1673 - 1.5613*i

0.1673 + 1.5613*i

Plugging these into (a + b + c)(a + b + d)(a + c + d)(b + c + d), we get -12.

I get the following:

Guest #1 has correctly identified the roots (approximately), but I think he/she has made a mistake in the final multiplication.