Gíup mk hết nha
C. Dạng 3 : Tính nhanh ( ghép số)
*5 x 20 x 4 x 2
* 94 + 87 + 81 – 71 – 77 – 84
D. Dạ ng 4: Tính nhanh ( Tổng dãy số )
* 7 + 7 + 7 + 7 + ……… + 7 – 777 ( Cã 111 sè 7 )
*2 – 4 + 6 – 8 + 10 – 12 + 14 – 16 + 18 – 20 + 22
*10 + 12 + 14 + 16 + ……… + 80
* 60 – 61 + 50 – 51 + 40 – 41 + 30 – 31 + 20 – 21 + 10 – 11 + 70
* 1999 – 2000 + 2999 – 3000 + 3999 – 4000 + 4999 – 5000 + 5999 – 1000
Dạng 5 : Tìm x
Tìm X
* X x 5 + 122 + 236 = 633
* 320 + 3 x X = 620
* 357 : X = 5 d 7
* X : 4 = 1234 d 3
* 120 – ( X x 3 ) = 30 x 3
* 357 : ( X + 5 ) = 5 d 7
* 65 : x = 21 d 2
* 64 : X = 9 d 1
* ( X + 3) : 6 = 5 + 2
* X x 8 – 22 = 13 x 2
* 720 : ( X x 2 + X x 3 ) = 2 x 3
* X+ 13 + 6 x X = 62
* 7 x ( X – 11 ) – 6 = 757
* X + ( X + 5 ) x 3 = 75
* 4 < X x 2 < 10
* 36 > X x 4 > 4 x 1
* X + 27 + 7 x X = 187
* X + 18 + 8 x X = 99
* ( 7 + X ) x 4 + X = 108
* ( X + 15 ) : 3 = 3 x 8
* ( X : 12 ) x 7 + 8 = 36
* X : 4 x 7 = 252
* ( 1+ x) +( 2 + x) + ( 3 + x) + ( 4 + x ) + ( 5 + x) = 10 x 5
* ( 8 x 18 – 5 x 18 – 18 x 3 ) x X + 2 x X = 8 x 7 + 24
C. ~5 x 20x 4 x 2
=(5 x 2 )x ( 20 x 4 )
=10 x 80
=800
* 94 +87+81-71-77-84
= ( 94- 84 ) + ( 87- 77) +( 81- 71)
=10 + 10 + 10
= 30
D.
* 2-4+6 -8 + 10 – 12 + 14- 16 + 18- 20+22
= ( 2+ 18) – (4+ 16) – ( 6+ 14) + (8 + 22 ) – ( 10 + 20 )
= 20 – 20 – 20 + 30 – 30
= 0
* 60- 61+ 50- 51+40-41 +30- 31 +20- 21 + 10- 11+ 70
= ( 60- 30) + (61 – 31) + (50 – 20) + ( 51- 21)+ ( 40- 10) + ( 41- 11) + 70
= 30 + 30 + 30 + 30 + 30 +30 + 70
= 250
E.
* X x 5 + 122 + 236 = 633
X x 5 + 358 = 633
X x 5 = 633 – 358=275
X = 275 : 5 = 55
* 320 + 3 x X = 620
3x X = 620- 320= 300
X = 300: 3 = 100
Milk làm đc tưng này nhé
Đáp án:
C= [20×5]x[4×2]
=100×8
=800
=[94-84]+[81-71]+[87-77]
=10+10+10
=30
D=[7×111]-777
=777-777
=0
=[22-2]+[20-10]+[18-8]+[16-6]+[14-4]+12
=20+10+10+10+10+12
=72
10+12+14+16+..+80
Số số hạng là :
( 80 – 10 ) : 2 + 1 = 36 ( số )
Tổng trên là :
( 80 + 10 ) . 36 : 2 = 1620
60-61+50-51+40-41+30-31+20-21+10-11+70
=[70-60]+[61-51]+[41-31]+[21-11]+[50-40]+[30-20]+10
=10+10+10+10+10+10+10
=70
1999 – 2000 + 2999 – 3000 + 3999 – 4000 + 4999 – 5000 + 5999 – 1000
=[5999-4999]+[3999-2999]+[5000-4000]+[3000-2000]+[1999-1000]
= 1000 + 1000 + 1000 + 1000 + 999
= 4999
Tìm x
x*5+122+236=633
x*5 = 633-122-236
x*5=275
x=275:5=55
320+3x=620
3x = 620-320 = 300
x =300:3=100
357 : x = 5d7 ?????????????
x: 4 = 1234
x=1234:4=308.5=617/2
120 -(x*3) = 30*3
120 – (x*3) = 90
x*3 = 120-90=30
x=30:3=10
xin tlhn