For what value of 'm' will the quadratic equation x2 - mx + 4 = 0 have real and equal roots? Select:
A) 16
B) 8
C) 2
D) -4
E) Choice (B) and (C)
Explanatory Answer   Any quadratic equation of the form ax2 + bx + c = 0 will have real and equal roots if its discriminant b2 - 4ac = 0.   In the given equation x2 - mx + 4 = 0, a = 1, b = -m and c = 4.   Therefore, b2 - 4ac = m2 - 4(4)(1) = m2 - 16.   The roots of the given equation are real and equal.   Therefore, m2 - 16 = 0 or	m2 = 16 or m = +4 or m = -4.   Hence, answer choice (-4)
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For what value of 'm' will the quadratic equation x2 - mx + 4 = 0 have real and equal roots?