Question

求2x²-7x+2的最小值

Answer 1

2x²-7x+2
=2(x²-7/2x+49/16)-33/8
=2(x-7/4)²-33/8
≥-33/8
∴2x²-7x+2的最小值是-33/8

Answer 2

2x²-7x+2=2(x²-7/2*x)+2
=2(x²-7/2*x+49/16-49/16)+2
=2[(x-7/4)²-49/16]+2
=2(x-7/4)²-49/8+2
=2(x-7/4)²-33/8
所以它的最小值为-33/8

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