(3a+1)(2a+3)-6(a-1)(a+2)其中a=-3,

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(3a+1)(2a+3)-6(a-1)(a+2)其中a=-3,

(3a+1)(2a+3)-6(a-1)(a+2)其中a=-3,
(3a+1)(2a+3)-6(a-1)(a+2)其中a=-3,

(3a+1)(2a+3)-6(a-1)(a+2)其中a=-3,
=6a²+11a+3-6a²-6a+12=5a+15=-15+15=0

(3a+1)(2a+3)-6(a-1)(a+2)
=6a^2+11a+3-6a^2+6a+12
=17a+15
=17*(-3)+15
=-51+15
=-36

(3a+1)(2a+3)-6(a-1)(a+2)
=6a^2+11a+3-6a^2-6a+12
=5a+15
=-15+15
=0

(3a+1)(2a+3)-6(a-1)(a+2)
=6a²+11a+3-6a²-6a+12
=5a+15
当a=-3时,
5a+15=-15+15=0

(3a+1)(2a+3)-6(a-1)(a+2)
=6a²+11a+3-6a²-6a+12
=5a+15
当a=-3时
5a+15=5x(-3)+15= -15+15=0

直接代入就行了 得 0