(5a+2a^2-3-4a^3)-(-a+3a^3-a^2）
=5a+2a^2-3-4a^3+a-3a^3+a^2
=-7a^3+3a^2+6a-3
=7x8+3x4-6x2-3
=56+12-12-3
=53
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