先化简,再求值:(-a-2)(-a+2)-a(a-2),其中a=-1.

2025-06-21 06:07:31
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回答1:

(-a-2)(-a+2)-a(a-2)
=(-a)^2-2^2-a^2+2a
=a^2-4-a^2+2a
=a^2-a^2+2a-4
=2a-4
=2*(-1)-4
=-2-4
=-6