ĐỀỬĐẠỌĐẲĂ. Môn thi : TOÁN ( ĐỀ 138 ) Bài 1(2 điểm): !"#$%&'( #) ) *#) ) y x x= + − +',,-$./ 0''1 0' 234 56$&7897:; #* Bài 2(3 điểm): ;75</,+= # # > x y x y xy x y x y + + = + + − − + + − = # x y R ∈ 75</,+= *& $ $ *# & x x x x x+ = − #? x R ∈ @ +''$ 075</,+&8$2/;'$,/ A B CD = E E # *F/ # D# BF/ D D m x m m x − − + − + − = − Bài 3(1 điểm): GH;IJ$2&'/$J8K/$: LJJM&C$$$A @SA SB SC a= = = #&N *,$AIIJFOF56FP9 0'&$IMJM&*Q0Q$3($27 *JR&* Bài 4(2 điểm): QQ$7:= *F# x x dx + ∫ ,/'S7T/A Uxy $ 0'#@C*VW775</,+ 5X/T/HY8&$Z $[8H5</$$,-$\& UxyGA]^&$H;Q$&'/$]^_P* Bài 5(1 điểm): ,/3K//&?;\& U`9a$ 5X/T/H = C# x t y t t R z t = + = + ∈ = + 5X/T/H F /&89$%&&'S7T/#]=`b9bM#^=`c9cabBM*\F/& 0' $%&HH *d75</,+ 5X/T/H @ Y8&#C@C !/X$Z& 5X/T/H H FOF56AJ&$&'/$J$: L* Bài 6(1 điểm): x, y, z ≥ @x y z+ + = *G/'= @ @ @ @ x y z y z x + + ≥ + + + ************************************ Đáp Án ĐỀỬĐẠỌĐẲĂ. Môn thi : TOÁN ( ĐỀ 138) J= 0' UH8/ e0' f2'(= #) ) *#) ) y x x= + − ⇔ 9M` D g` c# fhe=iC F' C F' x x y y →−∞ →+∞ = +∞ = +∞ C @ j D D C j C y x x y x x= − = ⇔ = = ± fJJ= *B fe\$ k/3/ C$$," *B fd k/ " *B 0' f\#&= Ox∈ '134 56$ #&7897:;* fe5X/T/H Y8&?;(/2$3$275</,+=9M3#`g& fHF$%$L3;7&8$2/;'= D @ # # D D x x k x a I x x k − + = − − = *B f2 # # k I A x = ⇔ − = S$ D # # @ D # x x k B x ax − = − + = *B f1;#$L$&'U789H89PFH=9M*dW9 0134 56$@7 897?#$O %F;#J7$2/;'7#`C3?`3$ ± G$F 75</,+#7$2/'7`3$ ± *B ^= @ @ a a− ≠ < − ≠ >hoÆc *B J= UH8/ e0' 0' f; # # B # # l# # m > x y x y x y − + − = ⇔ − − − + − = *eS u x v y = − = − 8 56$; B # > u v uv u v + = + = *B f,& 56$= @ * u v u v + = = Cf,& 56$= u x v y = − = = − = S$ u x v y = − = = − = *B @ x y = ⇒ = S$ @ x y = = *B 0' fe= $ x ≠ *] @ @ $ $ *#$ x x x x x⇔ + = − *B # $ *$ *# $ x x x x x⇔ + − = *B $ C $ x x x x⇔ + = − = *B C &,$& C# D x k x l k l Z π π π ⇔ = − + = + ∈ *B @ 0' f] E E # *F/ # # BF/ # m x m x m ⇔ − − − − − + − = feS [ ] E B F/ # CD C t x x t = − ∈ ⇒ ∈ − *B 8 56$7= B # t t m f t t t − + = = − + C D D j# C j# # t f t f t t t t − = = ⇔ = ± − + *B fVW7JJ$%&n#, A [ ] C− P9n#F-$J, A [ ] C− o @C @ m ∈ − _&'p [* *B J@= 0' f: 5X/$&$%&GH;A1 LIF,8/ 0'$%&$A *B fQ 56$ @ * @D S ABC a V = *B f 56$ * * * q S MNC S ABC V V= *B @ *J * o o @D * q r S ABC a V V⇒ = = *B JD= 0' fQ *F# I x x dx = + ∫ feS @ F# @ x du dx u x x dv x dx v x = = + + ⇒ = = D @ *F# @ @ x I x x dx x ⇒ = + − + ∫ *B fQ D l m *** @ D x J dx x dx x x π = = − + = = − − + + ∫ ∫ *B fdW9 D *F @ q > I π = + + *B 0' f1/&$2 # CC #C *P a Q b a b> > fH$27= x y a b + = * *B HY8&#@C @ @ * * @ab a b ab + = ⇒ ≥ ⇒ ≥ *sP8t/`9,&3$L 3 > @ a b a b = = ⇒ = *B f2 * * @ OPQ S a b ∆ = ≥ * OPQ S ∆ _P# @= 3$L3 > a b = = *B fdW9H$27= > x y + = *B JB= 0' fH $27= C# @ x t y t t R z t = = − + ∈ = − f+' 56$#CC *B @ &$2J#cCcCc# Cgc C@g # 3=J3$3$ t t ⇒ ≠ ≠ f&'/$J$: L # l m # IB IC AB AC = = uuur uuuur ur * *B *** t t = ⇔ ⇔ = * *B f1 2$27H @ = @ C# x y t R z t = = ∈ = + *B Bài 6: 0' &$2=dc@M @ @ @ # # # x y z y z x y z x + + + + + + + + *B @ @ > # D D x x y VT y y + ⇔ + = + + + + @ @ # D y y z z z + + + + + + @ @ # D z z x x x + + + + + + *B > > > @ @ @ > @ @ @ D > > > x y z VT + ≥ + + *B > @ @ @ q # r VT x y z⇒ + ≥ + + = > @ q @ q @ @ VT VP⇒ ≥ − = − = = # 7$' #sP8t/`9,&3$L3`M9MaM *B D . ĐỀỬĐẠỌĐẲĂ. Môn thi : TOÁN ( ĐỀ 138 ) Bài 1(2 điểm): !"#$%&'( . z y z x + + ≥ + + + ************************************ Đáp Án ĐỀỬĐẠỌĐẲĂ. Môn thi : TOÁN ( ĐỀ 138) J= 0' UH8/ e0' f2'(=