头脑风暴1(2022广州市白云中学高一上月考)
解答下列问题:
(1)已知
a
﹥
b
﹥
c
﹥0,求证:
;
(2)若
,
B
={
y
|
y
=
b
2
-3
a
-4
c
+2},
C
={
z
|
z
=
c
2
+
a
-
b
+1},求证∀
a
,
b
,
c
∈
R
,(
A
∪
B
∪
C
)∩
R
+
≠∅.