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2ใคใฎ้ขๆฐ f(x)=-x+1, g(x) = x2 ใซใคใใฆ,ๅฎๆฐๅ
จไฝใฎ้ๅใๅ
จไฝ้ๅใจ
ใ,ใใฎ้จๅ้ๅ A, B ใ A = {f(x)-1โฆxโฆ2}, B={g(x)|1 โฆ x โค 3} ใจ
ๅฎใใใ ้ๅ ANB, ANB ใๆฑใใใ
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โขๅฎๆฐๅ
จไฝใฎ้ๅใR ใง่กจใใใใใๅ
จไฝ้ๅใจใใใRใฎ2ใคใฎ้จๅ้ๅ
A={x||x-1|<โ5},B={x|-kโฆxโฆk}ใ่ใใใ ใใ ใ, kใฏๆญฃใฎๅฎ
ๆฐใจใใใ
(1) ABใจใชใใใฎๅคใฎ็ฏๅฒใๆฑใใใ
(2) AโฉB=ร ใจใชใใใฎๅคใฎ็ฏๅฒใๆฑใใใ
(3) AUBใซๅฑใใๆดๆฐใฎๅๆฐใ7ๅใจใชใkใฎๅคใฎ็ฏๅฒใๆฑใใใ
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โฃ
a,x ใๅฎๆฐใจใ, ้ๅ A = {2,4,2x3x-2}, B ={3, x2+ax+a},
C = {1, x2+(a+1)x - 3} ใ่ใใใ
(1) A = {2, 3, 4} ใจใชใxใฎๅคใฏ
|ใงใใใ
(2) 2B ใใค BCAใจใชใฮฑ, xใฎๅคใฎ็ต (ฮฑ, x)ใฏๅ
จ้จใง ็ตใใใ
(3) B=C ใจใชใฮฑ, xใฎๅคใฎ็ตใฏ (a,x)=(
ๆกไปถใจใงใใใ
4
O
ใๆๅณ
ๅไพใฏ
ใพ
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ใ
ๅ
โค ้ๅUใ1ใใ9ใพใงใฎ่ช็ถๆฐใฎ้ๅใจใใใUใฎ้จๅ้ๅ A,B,C ใ
AUB = {1, 2, 4, 5, 7, 8, 9, AUC = {1, 2, 4, 5, 6, 7, 9},
BUC={1,4,6,7,8,9}, AโฉB ={4, 9}, AโฉC = {7},
BโฉC={1}, AโฉBNC = ร
ใๆบใใใจใ
(1) ้ๅ A ใๆฑใใใ
(2)้ๅ BC ใๆฑใใใ ( ๆฑไบฌๅฝ้ๅคง )
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