问题 解答题

化简

(1)2(2a2+9b)+3(-5a2-4b)

(2)3(x3+2x2-1)-(3x3+4x2-2)

答案

(1)原式=4a2+18b-15a2-12b

=-11a2+6b;

(2)原式=3x3+6x2-3-3x3-4x2+2

=2x2-1.

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