mẹo giải phương chứa căn thức
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Mẹo Giải Phương Chứa Căn ThứcTRANSCRIPT
BA TUYT CHIU GII PHNG TRNH-BT PHNG TRNH CHA CN THC (Cm nang n thi i hc!)
TG: Ng Vit Vn-o Th Hu Cc thi i hc nhng nm gn y yu cu hc sinh gii PT c cha cn thc kh phc tp, hn na nhiu hc sinh qun, yu, thiu phn kin thc phn ny. Do vy ti trnh by tng i h thng cc bn lp 12 n li, cc bn lp 10 v 11 sm lm quen v tp dt, hy vng t nhng nh hng cc bn s d dng lnh hi kin thc t cc ti liu tham kho v gio vin trn lp
( Rt gn+lu tha hai v pt+a thnh PT tch1.
iu kin
Pt
EMBED Equation.DSMT4
EMBED Equation.3
EMBED Equation.DSMT4 2. (H D 05)
S: x=3
Bin trong cn thnh BP v b khi cn c:
3.
K:
Bnh phng hai v do khng m.di th!
(Do th hai v khng m )
4. (H A 04)
S:
K, quy ng MS, c: , y l bi c bn
5. (H A 05)
S: [2; 10], Bi hai cn, bnh phng hai ln
K: x
6.
Bpt:
K:
TH1: ; Pt:
(Bnh phngdi th!)
V ,
Nn Pt VN ( khn th!)
TH2:: Pt
S: x=1
7. (D b D 06)
S: x=4; x=5, a thnh tch, nh phn tch trong cn v nhm
K:
Pt:
8. (H A 10)
S:
K: x
MS lun dng v cn nh hn 1,
Bpt:
n y dng BT BNC
hoc BP v nhm li
9. (H B 10)
S: x=5
K: ; D on nghim l 5, ta s to ra hai lin hp ng vi hai cn, sao cho c nhn t x-5, ta lm nh sau: sau khi nhn lin hp v ra PT tch c mt nhn t lun dng trn D
( Rt gn, phn tch ri t n ph10.
Ta t ta c , ta c hoc
11. (H A 02) Error! Objects cannot be created from editing field codes.
S: x=5
K:
t ,
ta c: t2-t-12=0
12. (H NT )
S: x=1
Chia TH xt. Bnh phng kt hp cc b nghch o bng cch t =t
K
Pt:
EMBED Equation.313.
K: .
Bnh phng.
t Ta c: . Vy PT c nghim
.
14. : S:
K:
t ,
Bpt:
15.
t ta c phng trnh
EMBED Equation.3
EMBED Equation.DSMT4 t=1/2
T , gii tm x ta c x=4/3
16. S:
T nhn xt HT trong cn, v n bn ngoi cn ta t u= sau bin i hp l thay vo PT.
K:
Pt:
EMBED Equation.3 (C th dng PT bc hai)
17. S: x=-24; x=41
t n ph a v HPT i xng loi 1
K:
t:
Ta c:
18.
t
Phng trnh tng ng vi h sau:
c
( Dng hm s+nh gi hai v.19.
S:
Xt hm s: f(t)=
K:
Xt hm s: f(t)= c f(t)>0
x-1>3-x hay x>2
20.
K:
VT=
Nn x=1/2 l nghim duy nht21.
Nhn xt:
Suy ra
Phng trnh c nghim
22. S: x=6
t: v bnh phng
K: x15
u+v suy ra: (u-v)20 nn:
hay x=6. Th li t/m
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