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Trang 1so crAo pUC & pAo'r4to xam HQC 2013 - 2014
Thdi sian: t 50 phtit (kh6ng fA inat gian giao di)
- (DA thi gdm cd, 01 trang)
tsailkidia@'
a)Giaipkrumrgtrinh: cos3x+ ' =1+4cosl x +! icosl .x '- l
.oir*'''"""t )/ '' 3J
b) Cho phucrng trinh: ax' +(e + c)r + {a + r) = 0 (t) ce m$t nghiQm kh6ng
nh6 h.ryn 1 Chrmg minh rang phuong trinh axo +bx3 +cx'+dx+e-$ (Z) c6
nghiQrn,
BAi 2
'(4 di6w)
Ciro d6y s0 (r, ), ^ x6o dfnh nhu sau:
lro,o
t,
1r,,-, = ;(,'; + s) vur > o' -K6c dinh tdt ch"ac gii trf duong crla xo sao cho day cta cho ed gi6i han
Lrftu h7n
tsAi 3 ft di€rn)
Cjno trt diOn S,4^B C a6 SI,,SB,,SC d$i inOt vu6ng g6c vdi nhau" Gqi F/ vh O
ldn luct th truc tdm vh tam du&ng trdn ngoai tidp tam gi6c ABC ' Chfug minh rdng:
(ort)' ^ I
l I + / = _ _ -Isru ) - 4coslcr:sBcosC Bei 4 (3 Ci6m)
Tfrilr tdng: 5 - e'ue - !-z'qt+ * -Y2gtt +:2q+ + "" :' -
jsu.-=
ll- * ;"{ * - t 42 ' "7 .4j ' 2015.4t002 ' Bii 5 (3 di:6m)"
Cho c; b;r >0 thoa rn&n a + b + c + abc= 4 " Chirng minh rEng:
^fr, +, J, + r*7f17=t; {a + b+c)'
H6t