posted by Shay on .
Determine the value(s) of k for which
has equal and real roots.
a x^2 + bx + c = 0 has two different roots if the discriminant D defined as:
D = b^2 - 4 a c does not equal zero.
If D = 0 then there is one root. That root is then real if b/a is real. In this case this means that:
(k-2)^2 + 8k = 0 --->
(k+2)^2 = 0 --->
k = -2
k must also be real and -2 is real, so k = -2 is a valid solution.