问题 解答题

化简:

(1)x-2y+(2x-y);

(2)(3a2-b2)-3(a2-2b2).

答案

(1)原式=x-2y+2x-y

=x+2x-2y-y

=3x-3y,

(2)原式=3a2-b2-3a2+6b2

=5b2

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