已知3x+7y+4z=35,x+5y+2z=40,则x+y+z=______.-数学

题目简介

已知3x+7y+4z=35,x+5y+2z=40,则x+y+z=______.-数学

题目详情

已知3x+7y+4z=35,x+5y+2z=40,则x+y+z=______.
题型:填空题难度:中档来源:不详

答案

将两式组成方程组得
3x+7y+4z=35
x+5y+2z=40

①-②得,2x+2y+2z=-5,
∴x+y+z=-class="stub"5
2

故本题答案为:-class="stub"5
2

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