Question

已知:|X1-1|+|X2-2|+|X3-3|+.....+|X2012-2012|+|X2013-2013|=0

求:2^X-2^X2-2^X3-....-2^X2012+2^X2013的值

Answer 1

已知:|X1-1|+|X2-2|+|X3-3|+.....+|X2012-2012|+|X2013-2013|=0
则X1-1=0 X2-2=0 X3-3=0…….....X20122012=0 X20132013=0
X1=1 X2=2 X3=3 ……..... X2012=2012 X2013=2013=0
2^X1-2^X2-2^X3-....-2^X2012+2^X2013
=2^1-2^2-2^3-....-2^2012+2^2013
=2^1-(2^2013-2)+2^2013
=2+2
=4

Answer 2

4-a²/a²+6a+9 ÷ [a-2/2a+6 ]+2
=(2+a)(2-a)/(a+3)²÷[(a-2)/2(a+3)]+2
=(2+a)(2-a)/(a+3)²*2(a+3)/(a-2)+2
=-2(a+2)/(a+3)+2
=2/(a+3)
=4

Answer 3