T43 Cong Hai So Nguyen Cung Dau

8/3/2019 T43 Cong Hai So Nguyen Cung Dau

1/15

Nhit lit cho mng

cc thy c gio v d hi tho

Mn ton lp 9

9B

Ng-i thc hin: Nguyn Th NgcH-ng

Tr-ng THCS Quang Trung

6D

Nhit lit cho mng

cc thy c gio v d gi Mn Ton lp6D

Kim nh Thi

Tr-ng THCS Phm Cng Bnh


2/15

KIM TRA BI C

Khong cch t im a n im 0 trn trc s l gitr tuyt i ca s a.

P DNG:

Th no l gi tr tuyt i ca mt s nguyn a.p dng tnh:

pn

a, =12 0 3

-2 -1 0 +1 +2 +3 +4 +5 +7+6 +8 +9 +11+10 +12

12

!12)a !0)b ! 3)c

!

12)a !0)b!

3)c


3/15

Tp hp s nguyn c chia thnh baonhiu b phn ?A:Tp hp s nguyn c chia thnh 3 bphn:

+ Cc s nguyn dng.+ Cc s nguyn m.+ S 0.

Tp hp cc s nguyn c vit l:

Z = _ a...; 3; 2; 1;0;1;2;3;...


4/15

Tit 43: CNG HAI S NGUYN CNG DU

1. Cng hai s nguyn dng

Em c nhn xt gv s nguyn dngv s t nhin khc

0?Cc s nguyndng chnh lcc s t nhin

khc 0. Vy cng hai snguyn dng

chnh l cng hai st nhin.


5/15

+4

+2

+6

-2 -1 0 +1 +2 +3 +4 +5 +7+6 +8 +9

Nh vy: (+4) + (+2) = +6

P DNG, TNH: a, (+3) + (+5) =

b, (+139) + (+41) =

+8

+180

V d: Tnh: (+4) + (+2)




6/15

2. Cng hai s nguyn mV d: Nhit Mt-xc-va vo bui tra l -30C. Hinhit bui chiu cng ngy l bao nhiu, bit nhit

gim 20

C so vi bui tra?

-2 -3

-5

-4 -3 -2 -1 0 1 2-5-6-7

Tnh (-3) + (-2) = -5




7/15

?1

Qua bi tp ny em hy cho bit muncng hai s nguyn m ta c th lm

nh th no?

2. Cng hai s nguyn m

Tnh v nhn xt kt qu ca

(-4) + (-5) vKt qu: (-4) + (-5) = -9


` -4` + `-5`

` -4` + `-5` = 9

(-4)+(-5)= -(` -4` + `-5`)



8/15

Mun cng hai s nguyn m, ta cng hai gi tr tuyti ca chng ri t du ( - ) trc kt qu.

Thc hin cc php tnh:

a, (+37) + (+81)

b, (-23) + (-17)

?2

17

2. Cng hai s nguyn m

= 118


= - ( 23 + 17)

= - 40

(-17) + (-54)

= - (` -17` + `-54`)

= - ( 17 + 54) = - 71



9/15

3. Luyn tp2. Cng hai s nguyn m1. Cng hai s nguyn dng

Bi 23/ Sgk: Tnh


a, (-7)+(-14)

b, (-35)+(-9)

= - (7+14) = - 21

= - (35+9) = - 44


10/15

Bi 24: Thc hin cc php tnh sau:

a, (-5) + (-248)

b, 17 + `-33` =

c, `-37` + `+15`

= - (5+ 248 )

= - 253

17 + 33 = 50

= 37 + 15= 52

Tit 43: CNG HAI S NGUYN CNG DU1. Cng hai s nguyn dng2. Cng hai s nguyn m3. Luyn tp


11/15

Nhiet o hien tai cua phong lanh la -

5oC. Nhiet o tai o se la bao nhieuo C neu nhiet o giam 2oC

-7 -6 -5 -4 -3 -2 -1 0 +1

-7

Tit 43: CNG HAI S NGUYN CNG DU1. Cng hai s nguyn dng2. Cng hai s nguyn m3. Luyn tp


12/15

(+4) + ( +2) =(+4) + ( +2) =

-1 0 +1 +2 +3 +4 +5 +6 +7

+ 4+ 2

+ 6

4 + 2 =4 + 2 = 66

Quan sat chuyen ong cua chamo tren truc so roi at ra phep

toan.

3. Luyn tp2. Cng hai s nguyn m




13/15

1 2 3

E

m c nhn xt gi v kt qa tng ca hai snguyn m, tng ca hai s nguyn dng

Tng ca hai s nguyn m l mt s nguyn m,

Tng hai s nguyn dng l mt s nguyn dng

VUI NHN QU T NG GI NOEL

Bn tr li rt tt, ban xng ngnhn cmt im 10 t ng gi

Noel

Em hy tnh kt qu ca php tnh: (-25) + (-38) + (- 47)

Kt qu: -110Bn tnh rt tt, bn xng ng nhn cmt trng pho tay do ng gi Noel nh

cc bn trong lp gi ti bn

Bn tnh rt tt, ng gi Noel strao cho bn mt trng pho tay

thng qua cc bn ca lp.

Kt qu: -90C

Nhit lc 6 gi ti ti Pari ( Php) l -20C. n 8gi ti nhit gim thm 30C, n 10 gi m

nhit li gim thm 40C na. Hi nhit lc 10gi m ti Pari l bao nhiu?


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HNG DN V NH:

-Hc thuc quy tc cng hai s nguyn cng du

-Vn dng quy tc lm cc bi tp trong SGK v SBT


15/15

Xin chn thnh cm n cc Thy c gio v cc Em

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T43 Cong Hai So Nguyen Cung Dau