函数f(x)=x²+bx+1的最小值,则实数b=答案是因为f(x)=二次函数,二次项系数1>0,则最小值为f(-b/2)=b²/4-b²/2+1=0,解得b=±2b²/4-b²/2这步怎么来的
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![函数f(x)=x²+bx+1的最小值,则实数b=答案是因为f(x)=二次函数,二次项系数1>0,则最小值为f(-b/2)=b²/4-b²/2+1=0,解得b=±2b²/4-b²/2这步怎么来的](/uploads/image/z/2690362-10-2.jpg?t=%E5%87%BD%E6%95%B0f%28x%29%3Dx%26%23178%3B%2Bbx%2B1%E7%9A%84%E6%9C%80%E5%B0%8F%E5%80%BC%2C%E5%88%99%E5%AE%9E%E6%95%B0b%3D%E7%AD%94%E6%A1%88%E6%98%AF%E5%9B%A0%E4%B8%BAf%28x%29%3D%E4%BA%8C%E6%AC%A1%E5%87%BD%E6%95%B0%2C%E4%BA%8C%E6%AC%A1%E9%A1%B9%E7%B3%BB%E6%95%B01%EF%BC%9E0%2C%E5%88%99%E6%9C%80%E5%B0%8F%E5%80%BC%E4%B8%BAf%28-b%2F2%29%3Db%26%23178%3B%2F4-b%26%23178%3B%2F2%2B1%3D0%2C%E8%A7%A3%E5%BE%97b%3D%C2%B12b%26%23178%3B%2F4-b%26%23178%3B%2F2%E8%BF%99%E6%AD%A5%E6%80%8E%E4%B9%88%E6%9D%A5%E7%9A%84)
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函数f(x)=x²+bx+1的最小值,则实数b=答案是因为f(x)=二次函数,二次项系数1>0,则最小值为f(-b/2)=b²/4-b²/2+1=0,解得b=±2b²/4-b²/2这步怎么来的
函数f(x)=x²+bx+1的最小值,则实数b=
答案是因为f(x)=二次函数,二次项系数1>0,则最小值为f(-b/2)=b²/4-b²/2+1=0,解得b=±2
b²/4-b²/2这步怎么来的
函数f(x)=x²+bx+1的最小值,则实数b=答案是因为f(x)=二次函数,二次项系数1>0,则最小值为f(-b/2)=b²/4-b²/2+1=0,解得b=±2b²/4-b²/2这步怎么来的
X用b/2去代,
f(b/2)=(b/2)^2+b*b/2+1
=b^2/4+b^2/2+1.