已知a+b=4,求-2(a+b)²+3a-17+3b的值
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已知a+b=4,求-2(a+b)²+3a-17+3b的值
已知a+b=4,求-2(a+b)²+3a-17+3b的值
已知a+b=4,求-2(a+b)²+3a-17+3b的值
∵a+b=4
∴﹙a+b﹚²=16
∴-2(a+b)²+3a-17+3b=-2(a+b)²+3﹙a+b﹚-17=-2×16+3×4-17=-37
-2(a+b)²+3a-17+3b
=-2(a+b)²+3(a+b)-17
=-2*4*4+3*4-17
=-32+12-17=-37
-2(a+b)²+3a-17+3b=-2(a+b)²+3(a+b)-17=-2X4²+3X4-17=-37
-2X16+3X2-17+3X2