Proof: the equation AX ^ 2 + 2x + 1 = 0 of X has at least one negative root if and only if a

Proof: the equation AX ^ 2 + 2x + 1 = 0 of X has at least one negative root if and only if a

adequacy:
When a = 0, 2x + 1 = 0, x = - 1 / 2
If a = 0, there must be real roots
Two sum = - 2 / A, two product = 1 / A
If a