If x4 + 2x3 + ax2 + bx + 9 is a perfect square, where a and b are positive real numbers, then the values of a and b are

If x4 + 2x3 + ax2 + bx + 9 is a perfect square, where a and b are posi

1.	If x4 + 2x3 + ax2 + bx + 9 is a perfect square, where a and b are positive real numbers, then the values of a and b are
A.	a = 5, b = 6
B.	a = 6, b = 7
C.	a = 7, b = 6
D.	a = 7, b = 8
Answer» D. a = 7, b = 8