9. The original formula = (a-b)-(-b) = a.

1 1. According to the meaning of the question, x-3 is nonnegative and 5-x is nonnegative, that is, 3≤x≤5.

So the original formula = 6-x+(10-x) =16-2x.

The answer c is correct.

12, 1 Xiao Ming's answer is wrong.

②√a^2=∣a∣= a(a & gt； 0) or -a (a

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