II. CHUAN BI CUA GV VA HS 1 Chuan bi cua GV:
IIL PHAN PHOI THOII LUONG
Bai nay chia lam 2 tiet:
IV TIEN TRINH DAY HOC
A. BAI CU
Cau hdi 1
Cho bat phuang trinh
i X - 6 x + 5 > x - l a) Giai bat phuong trinh tren vdi x >1.
b) Giii bat phuang trinh tren vdi x <1. c) Giai bat phuang trinh tren.
Cau hoi 2
Neu each giai ba't phuong : yjfix) > g(x) va ^Jf(x) < g(x)
B. BAI M 6 |
HOAT DONG 1
Bai 69.
Chira hai cau a) va b). a)
Hoat ddng cua GV Cau hdi 1
Phuang trinh da cho tuang duang vdi phuang trinh nao?
Hoat ddng ciia HS Ggi y tra Idi cau hdi 1
Cau hdi 2
Hay giai phuong trinh:
^"-^2
X + 1
Cau hdi 3
Hay giai phuang trinh:
2 o
' - 2 = - 2 .
x + 1
X + 1
Ggi y tra Idi cau hdi 2
Vdi dieu kien x 7^ - 1, phuang trinh tuang duang vdi
x ^ - 2 x - 4 = 0 hay x= 1±V5
Ggi y tra Idi cau hdi 3
Vdi dieu kien x 7^ - 1, phuang trinh tuang duang vdi
2
X + 2x = 0 hay x= 0 hoac x = - 2 . b)
Hoat ddng cua GV Hoat ddng cua HS Cau hoi 1
Tim dieu kien cua bat phuang trinh.
Cau hdi 2
Giai bat phuang trinh da cho.
Ggi y tra Idi cau hdi 1
xi^2.
Ggi y tra Idi cau hdi 2
Ba't phuong trinh da cho
vdi< Tire X - 2 3x + 4 ^ 3 . x - 2 Id ta cd X < — 3 tuong duong c) Hudng ddn.
Bat phuang trinh da cho tuong duong vdi
< - 1 hoac > 1
x - 3 x-3
d) Hudng ddn.
Phuang trinh da cho tuong duong vdi (-x + 7 ) ( 5 x - l ) = 0 Ddp sd. x-1 X = — HOAT DONG 2 Bai 70. Chiia cau b). Hoat ddng c u a G V Cau hdi 1 Vdi X > hay 2 phuang trinh da c h o . Cau hdi 2 Vdi X < — hay 2
phuang trinh da cho.
Cau hdi 3
Tim nghiem ciia bat trinh da cho. giai giai bat bat phuang Hoat ddng c u a H S Ggi y tra Idi cau hdi 1
Bat phuang trinh tuong duong v6i
9 3 4 x ^ + 2 x - 6 > 0 < : : > x < - - hoacx> 1.
2
G g i y tra Idi cau hdi 2
Bat phuang trinh tuong duong v6i
? 1
4x + 6 x - 4 > 0 <=>x<-2hoacx> - 2
Ggi y tra Idi cau hdi 3
( - a ) ; - 2 ] u [ l ; + « ) .
a) Hudng ddn.
Pha dau gia tri tuyet ddi va giai bat phuong trinh trong tirng trudng hgp.
Ddp sd. Tap nghiem cua bat phuong trinh la : S = [ ; + oo).
HOAT DONG 3
Bai 71.
Chiia cau a).
Hoat ddng ciia GV Cau hdi 1
Tim dieu kien xac dinh ciia phuang trinh.
Cau hdi 2
Giai phuang trinh da cho.
Hoat ddng cua HS
Ggi y tra Idi cau hdi 1
Dieu kien:
3-V29 , 3 + V29 X < hoac X > X < hoac X >
5 5
Ggi y tra Idi cau hdi 2
Phuang trinh da cho tuong duong vdi : r x > i
T hay X = 2. [.v^+2x-8 = 0
b) Hudng ddn.
DKXD cua phuang trinh : R.
Dat Vx + 3x +12 = / > 0 tir dd tim t va suy ra nghiem cua phuang trinh.
Ddp sd. X = 1 hoac x = 4.
HOAT DONG 4
Bai 72.
Chita cau a).
Hoat ddng ciia GV Cau hdi 1
Tim dieu kien xac dinh ciia bat phuang trinh.
Cau hdi 2
Giai bat phuang trinh da cho.
Hoat ddng cua HS Ggi y tra Idi cau hdi 1
Dieu kien: x < - 4 hoac x > - 2 .
Ggi y tra Idi cau hdi 2
Bat phuang trinh da cho tuong duong vdi:
b) Hudng ddn.
DKXD cua bat phuang trinh x < -2 hoac x > 5. Bat phuang trinh tuong duang vdi :
| x > 2
3x^-13x + 2 6 > 0
Ddp so. X > 5. c) Hudng ddn.
Xem hudng din trong SGK.
Ddp sd. X = 1 hoac x = 4.
HOAT DONG 5
Bai 73.
Chira cau a).
Hoat ddng cua GV Cau hdi 1
Tim dieu kien xac dinh ciia bat phuang trinh.
Cau hdi 2
Giai bat phuang trinh da cho.
Hoat ddng cua HS Ggi y tra Idi cau hdi 1
Dieu kien: x < - 3 hoac x > 4.
Ggi y tra Idi cau hdi 2
Bit phuang trinh da cho tuang duong vdi :
f x > l
X < 1 hoac < hay • [ x - l l > 0
X e (-co ; - 3 ] u [13 ; + oo).
b) Hudng ddn.
DKXD ciia bat phuang trinh x < -2 hoac x > 6. Bat phuang trinh tuong duong vdi :
X < — hoac 2 3 X > - - 2 3x^+16x + 2 1 < 0 Ddp sd. X < - 2 . c) Hudng ddn.
Dieu kien xac dinh cua bat phuang trinh la: x >-5 va x 7^ 1.
f l - x > 0 f l - x < 0 Bat phuang trinh da cho tuong duang vdi < hoac <^
[ V x - 5 < l - x • [ V x - 5 > l - x Ddp so. S = [- 5 ; - 1] u (1 ; + 00). HOAT DONG 6 Bai 74. Hoat ddng ciia GV Cau hdi 1
Hay neu dang ciia phuang trinh.
Cau hdi 2
Dat t = x", t thoa man dieu kien gi?
Cau hdi 3
Vdi
Hoat ddng cua HS Ggi y tra Idi cau hdi 1
Day la phuong trinh trung phuang.
Ggi y tra Idi cau hdi 2
t > 0 .
Ggi y tra Idi cau hdi 3
Phuang trinh da cho v6 nghiem khi
phuang trinh da cho v6 nghiem khi nao?
Cau hdi 4
Phuang trinh da cho cd hai nghiem phan biet khi nao?
Cau hdi 5
Phuang trinh da cho cd bd'n nghiem phan biet khi nao?
am.
Nghia la m < - 1 hoac m> — 4
Ggi y tra Idi cau hdi 4
Phuang trinh da cho cd hai nghiem
phan biet khi f(t) chi cd mot
nghiem duong.
Nghia la m e (-1 ; 1 ) A J { - } .
Ggi y tra Idi cau hdi 5
Phuang trinh da cho cd 4 nghiem
phan biet khi f(t) eo 2 nghiem
duong. Nghia la 1 < m < — 4 HOAT DONG 7 Bai 75. H o a t d d n g ciia G V C a u hdi 1
Hay neu dang ciia phuang trinh.
C a u hdi 2
Dat t = X" t thoa m a n dieu kien gi?
C a u hdi 3 Vdi
f(f) = (a-l)t^+at + a^-1 = 0.
phuang trinh da cho cd ba nghiem phan biet khi nao?
H o a t d d n g ciia HS Ggi y t r a Idi c a u hdi 1
Day la phuang trinh triing phuong.
Ggi y t r a Idi c a u hdi 2 t > 0 .
G g i y t r a Idi c a u hdi 3
Phuang trinh da cho vd nghiem khi
f(t) eo mot nghiem t = 0, nghiem
thii hai duong. Nghia la a = - 1 .