Determine which functions have two real number zeros by calculating the discriminant, b2 - 4ac. Check all that
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f(x) = x2 + 6x + 8
g(x) = x2 + 4x + 8
h(x) = x2 - 12x + 32
k(x) = x2 + 4x - 1
p(x) = 5x2 + 5x + 4
t(x) = x2 - 2x - 15