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证明下列不等式:(1)若x,y,z∈R,a,b,c∈R+,则b+cax2+c+aby2+a+bcz2≥2(xy+yz+zx)(2)若x,y,z∈R+,且x+y+z=xyz,则y+zx+z+xy+x+yz≥2(1x+1y+1z)
题目详情
证明下列不等式:
(1)若x,y,z∈R,a,b,c∈R+,则
x2+
y2+
z2≥2(xy+yz+zx)
(2)若x,y,z∈R+,且x+y+z=xyz,则
+
+
≥2(
+
+
)
(1)若x,y,z∈R,a,b,c∈R+,则
b+c |
a |
c+a |
b |
a+b |
c |
(2)若x,y,z∈R+,且x+y+z=xyz,则
y+z |
x |
z+x |
y |
x+y |
z |
1 |
x |
1 |
y |
1 |
z |
▼优质解答
答案和解析
证明:(1)若x,y,z∈R,a,b,c∈R+,
∵
x2+
y2+
z2-2(xy+yz+xz)=(
x2+
y2−2xy)+(
y2+
z2−2yz)+(
x2+
z2−2xz)
=(
x−
y)2+(
y−
z)2+(
∵
b+c |
a |
c+a |
b |
a+b |
c |
b |
a |
a |
b |
c |
a |
a |
c |
c |
a |
a |
c |
=(
|
|
|
|
|
作业帮用户
2017-10-03
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