Tìm điều kiện xác định rồi rút gọn A? Tìm x để A = -3?
bai 6
A=2+x/2-x - 4x^2/x^2-4 - 2/2-x/2+x
a) tim dieu kien xac dinh roi rut gon a
B) tim x de a= -3
Bai 7
A) -1/2x+2=5/2x -1
B) 10-2x=-3(4-x)+1
C) x-x+1/3=2x+1/5
Bai 8 1 chiec thuyen xuoi dong tu a deb b sau do di nguoc dong tu b den a . Thoi gian xuoi dong la 5 gio . Thoi gian nguoc dong la 6 gio . Tinh van toc thuc te cua thuen , biet van toc dong nuoc la 1km/h
Bai 9
1 ca no chay tren cung 1 khuc song tu a den b . Biet rang khi di xuoi dong tu a den b ca no mat 8 h . Nguoc dong song tu b den a ca no mat 10 h . Tinh khoang cach ab .biet van toc dong nuoc la 2km/h
Bai 10
Cho tam giac abc vùog tai a (ab<ac) va trung tuyen ad . Qua d ke duong thang vuong goc oi ad cat ac lan luot tai e , f chung minh
A) tam giac abc dong dang voi tam tam giac aef
B) bc^2 = 4 de.df
Bai11
Cho tam giac abc vuong tai a duong cao aH (Hthuoc bc)
A) CHUNG MINH TAM GIAC HBA DONG DANG VOI TAM GIAC ABC
B) CHUNG MINH AH^2 = HB.HC
C) TIA PHAN GIAC GOC AHC CT AC TAI D
CHUNG MINH HB/HC=AD^2/DC^2
bai 12
Cho tam giac abc vuong tai a co ab=3cm , ac=4cm , duong cao ah . Tren canh bc lay e sao cho ab=be
A) chung minh tam giac hba dong dang voi tam giac abc
b) be^2 =bh.bc
c) bc va ah
D) TIA PHAN giac goc abc cat ac tai d
Tinh ti so Sced/Sabc
Bai 13
Cho tam giac abc nhon duong cao ah . Ke hi vuong goc ab va hkvuong goc voi ac
A) ah^2 = ai.ab
B) tam giacahk dong dang voi tam giac acb
C_ duong phan giac cua goc ahb cat ab tai e . Biet eb/ab =2/5 . Tinh ti so bi/ai
Bai 14 cho tam giac abc vuong tai a co duong cao ah . Qua c ve duong thang // voi ab va cat ah tai d . Biet ab=20cm ac=15cm
A) chung minh tam giac abc dong dang voi tam giac hba va tinh bc , ah
B) ac ^2 =ab.dc
C) goi I va K lan luot la trung diem cua ab va cd
Chung minh i , h, k thang hang
A=2+x/2-x - 4x^2/x^2-4 - 2/2-x/2+x
a) tim dieu kien xac dinh roi rut gon a
B) tim x de a= -3
Bai 7
A) -1/2x+2=5/2x -1
B) 10-2x=-3(4-x)+1
C) x-x+1/3=2x+1/5
Bai 8 1 chiec thuyen xuoi dong tu a deb b sau do di nguoc dong tu b den a . Thoi gian xuoi dong la 5 gio . Thoi gian nguoc dong la 6 gio . Tinh van toc thuc te cua thuen , biet van toc dong nuoc la 1km/h
Bai 9
1 ca no chay tren cung 1 khuc song tu a den b . Biet rang khi di xuoi dong tu a den b ca no mat 8 h . Nguoc dong song tu b den a ca no mat 10 h . Tinh khoang cach ab .biet van toc dong nuoc la 2km/h
Bai 10
Cho tam giac abc vùog tai a (ab<ac) va trung tuyen ad . Qua d ke duong thang vuong goc oi ad cat ac lan luot tai e , f chung minh
A) tam giac abc dong dang voi tam tam giac aef
B) bc^2 = 4 de.df
Bai11
Cho tam giac abc vuong tai a duong cao aH (Hthuoc bc)
A) CHUNG MINH TAM GIAC HBA DONG DANG VOI TAM GIAC ABC
B) CHUNG MINH AH^2 = HB.HC
C) TIA PHAN GIAC GOC AHC CT AC TAI D
CHUNG MINH HB/HC=AD^2/DC^2
bai 12
Cho tam giac abc vuong tai a co ab=3cm , ac=4cm , duong cao ah . Tren canh bc lay e sao cho ab=be
A) chung minh tam giac hba dong dang voi tam giac abc
b) be^2 =bh.bc
c) bc va ah
D) TIA PHAN giac goc abc cat ac tai d
Tinh ti so Sced/Sabc
Bai 13
Cho tam giac abc nhon duong cao ah . Ke hi vuong goc ab va hkvuong goc voi ac
A) ah^2 = ai.ab
B) tam giacahk dong dang voi tam giac acb
C_ duong phan giac cua goc ahb cat ab tai e . Biet eb/ab =2/5 . Tinh ti so bi/ai
Bai 14 cho tam giac abc vuong tai a co duong cao ah . Qua c ve duong thang // voi ab va cat ah tai d . Biet ab=20cm ac=15cm
A) chung minh tam giac abc dong dang voi tam giac hba va tinh bc , ah
B) ac ^2 =ab.dc
C) goi I va K lan luot la trung diem cua ab va cd
Chung minh i , h, k thang hang