- Gidi bdt phuang trinh la tim tdt cd cdc nghiem ihay tim tap nghiem) ciia bdt
v a^ ggi la tap xac dinh cua ba't phuang trinh.
HUONG DANG IAI BAI TAP SGK
Bai 21.
De giai bai tap nay, HS cin:
- Dgc kl li thuyet phin bien ddi tuong duong cac bat phuang trinh. - Xem lai khai niem : Dieu kien xac dinh cua bat phuang trinh. - Xem lai vi du trong SGK.
GV: Hudng ddn cdu b) theo cdc cdu hdi hoqt ddng sau:
Cau hdi Cau hdi 1
Khi binh phuang hai ve, hai phuang trinh tren da tuang duang hay chua?
Cau hdi 2.
Lap luan tren cd diing khdng?
Ggi y tra 161 Ggi y tra Idi cau hdi 1
Chua tuang duang vi chua dat dieu kien ciia phuang trinh.
Ggi y tra Idi cau hdi 2
1 Khdng diing, chang han — la nghiem ciia bat phuang trinh thii hai nhung khdng la nghiem ciia bat phuang trinh thir nha't.
Bai 22.
De giai bai tap nay, HS can:
- Dgc kl li thuye't phan bien ddi tuong duong cac bat phuong trinh. - Xem lai khai niem : Tap xac dinh va tap nghiem ciia bat phuang trinh. - Xem lai vi du trong SGK.
GV: Hudng ddn cdu b) theo cdc cdu hdi hoqt ddng sau:
Cau hdi Cau hdi 1
Tim didu kien vua bat phuang trinh.
Ggi y tra Idi Ggi y tra Idi cau hdi 1
Didu kien xac dinh cua bat phuang trinh la x > 3.
C a u hdi 2
Tim tap nghiem ciia bat phuang trinh.
G g i y tra Idi cau hdi 2
S = [ 3 ; + co).
Tap xac dinh va tap nghiem trung nhau.
Ggi y c a c cau edn lai.
a ) D K X D : x = O ; T = 0 .
c) DKXD X 9t 3 ; T = [2 ; 3) u (3 ; + 00). d ) D K X D x > 2 ; T = 0 .
Bai 23.
De giai bai tap nay, HS can:
- Dgc kl li thuyet phan bien doi tuong duong cac bat phuong trinh. - Xem lai khai niem : Tap nghiem cua bat phuong trinh.
- Xem lai vi du trong SGK.
GV: Hudng ddn cdu c) theo cdc cdu hdi hoqt ddng sau: