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(1)求证:xax−a2+yay−a2+zaz−a2=1x−a+1y−a+1z−a+3a(2)求证:(a+1a)2+(b+1b)2+(ab+1ab)2=4+(a+1a)(b+1b)(ab+1ab).

题目详情
(1)求证:
x
ax−a2
+
y
ay−a2
+
z
az−a2
1
x−a
+
1
y−a
+
1
z−a
+
3
a

(2)求证:(a+
1
a
)2+(b+
1
b
)2+(ab+
1
ab
)2=4+(a+
1
a
)(b+
1
b
)(ab+
1
ab
).
▼优质解答
答案和解析
(1)左边=
a+(x−a)
a(x−a)
+
a+(y−a)
a(y−a)
+
a+(z−a)
a(z−a)
=
1
a
+
1
x−a
+
1
a
+
1
y−a
+
1
a
+
1
z−a
=
1
x−a
+
1
y−a
+
1
z−a
+
3
a
=右边;
(2)∵(a+
1
a
)2+(b+
1
b
)2+(ab+
1
ab
)2-[4+(a+
1
a
)(b+
1
b
)(ab+
1
ab
)]
=a2+2+
1
a2
+b2+2+
1
b2
-4+(ab+
1
ab
2-(a+
1
a
)(b+
1
b
)(ab+
1
ab

=a2+
1
a2
+b2+
1
b2
+(ab+
1
ab
)[(ab+
1
ab
)-(a+
1
a
)(b+
1
b
)]
=a2+
1
a2
+b2+
1
b2
+(ab+
1
ab
)(
b
a
a
b

=a2+
1
a2
+b2+
1
b2
-a2-
1
a2
-b2-
1
b2

=0,
(a+
1
a
)2+(b+
1
b
)2+(ab+
1
ab
)2=4+(a+
1
a
)(b+
1
b
)(ab+
1
ab
).