Roots

Example: If the roots of x^3 + bx^2 + cx + d = 0 are -1, 2, 5, then b + c + d equals:
One method could be to expand (x+1)(x-2)(x-5) and then add b,c and d but there is a simpler method of obtaining the answer. Let's start with b.

-b/a is the sum of the roots. since a is 1, -b= -1 + 2 + 5. b=-6

c/a is the result of adding the product of the roots taken two at a time. (-1)(2) + (-1)(5) + (2)(5) = c/a.
c =3

-d/a is the product of the roots. -d/a = (-1)(2)(5). d = 10

b + c + d = -6 + 3 + 10 = 7

-Kevin