求证:无论P取何值,代数式2x²-x+3的值恒为正.)是x取何值时。打错了= =
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![求证:无论P取何值,代数式2x²-x+3的值恒为正.)是x取何值时。打错了= =](/uploads/image/z/5307691-67-1.jpg?t=%E6%B1%82%E8%AF%81%3A%E6%97%A0%E8%AE%BAP%E5%8F%96%E4%BD%95%E5%80%BC%2C%E4%BB%A3%E6%95%B0%E5%BC%8F2x%26%23178%3B-x%2B3%E7%9A%84%E5%80%BC%E6%81%92%E4%B8%BA%E6%AD%A3.%EF%BC%89%E6%98%AFx%E5%8F%96%E4%BD%95%E5%80%BC%E6%97%B6%E3%80%82%E6%89%93%E9%94%99%E4%BA%86%3D+%3D)
求证:无论P取何值,代数式2x²-x+3的值恒为正.)是x取何值时。打错了= =
求证:无论P取何值,代数式2x²-x+3的值恒为正.)
是x取何值时。打错了= =
求证:无论P取何值,代数式2x²-x+3的值恒为正.)是x取何值时。打错了= =
2x²-x+3=2(x²-2*1/4x+1/16-1/16)+3=2(x-1/4)²-1/8+3=2(x-1/4)²+23/8
∵2(x-1/4)²≥0 ∴2(x-1/4)²+23/8≥23/8
∴无论x取何值,代数式2x²-x+3的值恒为正.
也就是求2x²-x+3>0
2x²-x>-3
x²-x>-3分子2
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抱歉···我才初二 还解不了