计算:1/a-3 -1/a^2-9 -a-1/6+2a.

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计算:1/a-3 -1/a^2-9 -a-1/6+2a.
计算:1/a-3 -1/a^2-9 -a-1/6+2a.

计算:1/a-3 -1/a^2-9 -a-1/6+2a.
1/(a-3) -1/(a^2-9) -(a-1)/(6+2a)
=1/(a-3) -1/[(a-3)(a+3)] -(a-1)/[2(a+3)]
=2(a+3)/[2(a-3)(a+3)] -2/[2(a-3)(a+3)] -(a-1)(a-3)/[2(a-3)(a+3)]
=(2a+6)/[2(a-3)(a+3)] -2/[2(a-3)(a+3)] -(a^2-4a+3)/[2(a-3)(a+3)]
=[(2a+6) -2 -(a^2-4a+3)]/[2(a-3)(a+3)]
=(2a+6 -2 -a^2+4a-3)/[2(a-3)(a+3)]
=(-a^2+2a+4a+6 -2 -3)/[2(a-3)(a+3)]
=(-a^2+6a+1)/[2(a-3)(a+3)]

=1/(a-3)-1/(a+3)(a-3)-(a-1)/2(a+3)
=[2(a+3)-2-(a-1)(a-3)]/2(a+3)(a-3)
=(2a+6-2-a²+4a-3)/2(a+3)(a-3)
=(-a²+6a+1)/(2a²-18)