均值不等式练习总复习第一轮!1.求y=1-2x-x/3(x>0)的最值.并求出相应的x值.2.问x为何值时,函数y=√x(1-2x) (0一题是y=1-2x-(3/x)
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![均值不等式练习总复习第一轮!1.求y=1-2x-x/3(x>0)的最值.并求出相应的x值.2.问x为何值时,函数y=√x(1-2x) (0一题是y=1-2x-(3/x)](/uploads/image/z/5129033-41-3.jpg?t=%E5%9D%87%E5%80%BC%E4%B8%8D%E7%AD%89%E5%BC%8F%E7%BB%83%E4%B9%A0%E6%80%BB%E5%A4%8D%E4%B9%A0%E7%AC%AC%E4%B8%80%E8%BD%AE%211.%E6%B1%82y%3D1-2x-x%2F3%28x%3E0%29%E7%9A%84%E6%9C%80%E5%80%BC.%E5%B9%B6%E6%B1%82%E5%87%BA%E7%9B%B8%E5%BA%94%E7%9A%84x%E5%80%BC.2.%E9%97%AEx%E4%B8%BA%E4%BD%95%E5%80%BC%E6%97%B6%2C%E5%87%BD%E6%95%B0y%3D%E2%88%9Ax%281-2x%29+%280%E4%B8%80%E9%A2%98%E6%98%AFy%3D1-2x-%283%2Fx%29)
均值不等式练习总复习第一轮!1.求y=1-2x-x/3(x>0)的最值.并求出相应的x值.2.问x为何值时,函数y=√x(1-2x) (0一题是y=1-2x-(3/x)
均值不等式练习总复习第一轮!
1.求y=1-2x-x/3(x>0)的最值.并求出相应的x值.
2.问x为何值时,函数y=√x(1-2x) (0
一题是y=1-2x-(3/x)
均值不等式练习总复习第一轮!1.求y=1-2x-x/3(x>0)的最值.并求出相应的x值.2.问x为何值时,函数y=√x(1-2x) (0一题是y=1-2x-(3/x)
1.求y=1-2x-x/3(x>0)的最值.并求出相应的x值.
2x+3/x≥2√6,-2x-3/x≤-2√6,(当2x=3/x x²=3/2 x=√6/2时取等)
y≤1-2√6,∴x=√6/2时,ymax=1-2√6
2.问x为何值时,函数y=√x(1-2x) (00,且5x+7y=20 求x 乘 y的最大值.
20=5x+7y≥2√(35xy)
35xy≤100,xy≤20/7
5x=7y,x=2,y=10/7时,xy取得最大值20/7
5.已知x.y∈R,x+2y=4,求3^x+9^y的最小值
3^x+9^y≥2√[3^x*3^(2y)]=2*3^2=18
x=2y=2,x=2,y=1时,3^x+9^y取得最小值18
6.设x3 求y=2x+1/(x-3)的最小值.
y=2x+1/(x-3)=2(x-3)+1/(x-3)+6≥2√2+6
当 2(x-3)=1/(x-3)==>(x-3)^2=1/2
==>x=3+√2/2时,ymin=2√2+6
8.已知x>0 f(x)=x+5x+4/x的最大值.
f(x)=5x+4/x (去1个x吧)
≥2√20=4√5
5x=4/x ==>x²=4/5
==>x=2√5/5时,f(x)min=4√5