If x^2 - 4 = 0 and x < 0, which of the following must be equal to 0 ? Choose the correct choice from the following options:
A) x^2 - 9x B) x^2 - 9x + 20 C) x^2 - 2x + 3 D) x^2 + 2x - 3 E) x^2 + 5x + 6
x^2-4 = 0   x= +2 or x = -2   if we substitute x= -2 in the equation x^2 +5x+6 = 4-10+6= 
<gadget id="calculator">4-10+6</gadget>
<output>0</output>
0   x^2 + 5x + 6 is also the answer
<result>E</result>
If x^2 - 4 = 0 and x < 0, which of the following must be equal to 0 ?