1 makes sense when x≦-4.5, because the -2 power of (2x+9) equals the reciprocal of the quadratic power of (2x+9), and the denominator of the reciprocal cannot be 0.

2, 12, through power exponent operation, the m+n power of x = the m power of x times the n power of x =6*2= 12.

3, the square of B, A and B are reciprocal, then (the fourth power of A times the fifth power of B) = (the fourth power of A times the fifth power of B) =b, then the second power is the square of B.