题目内容
【题目】已知x2﹣2y+2的值是5,则﹣3x2+6y+2的值为_____.
【答案】-7
【解析】
由x2﹣2y+2的值是5,然后把代数式﹣3x2+6y+2化为﹣3(x2﹣2y+2)+8,再把代入求解即可.
解:当x2﹣2y+2=5时,
﹣3x2+6y+2
=﹣3×(x2﹣2y+2)+8
=﹣3×5+8
=﹣15+8
=﹣7
故答案为:﹣7.
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题目内容
【题目】已知x2﹣2y+2的值是5,则﹣3x2+6y+2的值为_____.
【答案】-7
【解析】
由x2﹣2y+2的值是5,然后把代数式﹣3x2+6y+2化为﹣3(x2﹣2y+2)+8,再把代入求解即可.
解:当x2﹣2y+2=5时,
﹣3x2+6y+2
=﹣3×(x2﹣2y+2)+8
=﹣3×5+8
=﹣15+8
=﹣7
故答案为:﹣7.