代数式2x²-3x+2的值为7,则x²-3/2x-1的值是多少
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代数式2x²-3x+2的值为7,则x²-3/2x-1的值是多少
代数式2x²-3x+2的值为7,则x²-3/2x-1的值是多少
代数式2x²-3x+2的值为7,则x²-3/2x-1的值是多少
2x²-3x+2
=2(x²-3/2x)+2=7
x²-3/2x=5/2
x²-3/2x-1=5/2-1=3/2
2x²-3x+2的值为7
2x²-3x+2=7
2x²-3x=5
x²-3/2x-1
=1/2(2x²-3x)-1
=5/2-1
=3/2
因为2x²-3x+2=7
解得 x=5/2 或x=-1
带入原式的
原式=-3/2或93/20