已知a+b=3,ab=-2,求(3a+5ab)-(3ab-3b)的值(注:

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已知a+b=3,ab=-2,求(3a+5ab)-(3ab-3b)的值(注:
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已知a+b=3,ab=-2,求(3a+5ab)-(3ab-3b)的值(注:
已知a+b=3,ab=-2,求(3a+5ab)-(3ab-3b)的值
(注:

已知a+b=3,ab=-2,求(3a+5ab)-(3ab-3b)的值(注:
(3a+5ab)-(3ab-3b)
=3a+5ab-3ab+3b
=3a+3b+2ab
=3×(a+b)+2ab
=3×3+2×(-2)
=9-4
=5

(3a+5ab)-(3ab-3b)=3a+5ab-3ab+3b=3(a+b)+2ab=9-4=5

(3a+5ab)-(3ab-3b)=3(a+b)+2ab=3*3+2*-2=5

展开即可。=3a+3b+2ab=3(a+b)+2ab=3*3-2*2=5

把括号拆开就好了。。
3a+5ab-3ab+3b=3(a+b)+2ab=3*3-2*(-2)=5

(3a+5ab)-(3ab-3b)
=3a+5ab-3ab+3b
=3a+3b+5ab-3ab
=3(a+b)+2ab
=3×3+2×(-2)
=9-4
=5