代数式(3x的二次方-4)-(2x二次方-5x+6)+(x二次方-5x)
=[3×(-2)²-4]-[2×(-2)²-5(-2)+6]+[(-2)²-5×(-2)]
=3×4-4-(2×4+16)+4+10
=8-24+14
=-2
已知x=-2,求代数式(3x的二次方-4)-(2x二次方-5x+6)+(x二次方-5x)的值.
已知x=-2,求代数式(3x的二次方-4)-(2x二次方-5x+6)+(x二次方-5x)的值.
数学人气:199 ℃时间:2019-09-23 14:56:03
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