x - 200 = 400 x 3 x + 130 = 200 - 100
b) 200 x 4 = ...... 300 x 2 = ......
200 x 2 = ...... 300 x 3 = ......
400 x 2 = ...... 500 x 1 = ......
100 x 4 = ...... 100 x 3 = ......
b) 200 x 4 = .800..... 300 x 2 = ..600....
200 x 2 = .400..... 300 x 3 = ...900...
400 x 2 = ...800... 500 x 1 = ..500....
100 x 4 = ..400.... 100 x 3 = .300.....
Tính nhẩm:
Cách làm: 200 x 3 = ?
Nhẩm: 2 trăm x 3 = 6 trăm
Vậy: 200 x 3 = 600
200 x 2 = 300 x 2 =
200 x 4 = 400 x 2 =
100 x 5 = 500 x 1 =
Học sinh nhẩm và ghi kết quả như sau:
200 x 2 = 400
200 x 4 = 800
100 x 5 = 500
300 x 2 =600
400 x 2 =800
500 x 1 =500
200 x 2 = 400 300 x 2 =600
200 x 4 = 800 400 x 2 =800
100 x 5 = 500 500 x 1 =500
tính nhanh :
100 x 200 + 200 x 500 + 200 x 400
100x200+200x500+200x400
=20000+100000+80000
=120000+80000
=200000
100 x 200 + 200 x 500 + 200 x 400
= 200 x ( 100 + 500 + 400 )
= 200 x 1000
= 200000
100x200+200x500+200x400
=20000+100000+80000
=120000+80000
=200000
100 x 3 + 400 . . . 100 +200 + 100 x 4
100 x 3 + 400 ... 100 + 200 + 100 x 4
= 100 x 3 + 400 = 700
= 100 + 200 + 100 x 4 = 700
=> 100 x 3 + 400 = 100 + 200 + 100 x 4
500 + x = 100 + 500
300 - x = 300 + 200
400 - x = 200 + 400
500 + x = 100 + 500
500 + x = 600
x = 600 - 500
x = 1001
300 - x = 300 + 200
300 - x = 500
x = 300 - 500
x = -200
400 - x = 200 + 400
400 - x = 600
x = 400 - 600
x = -200
k mk nha mk k l
ại ^_^
500 + 100 = 100 + 500
300 + 200 = 300 + 200
400 + 200 = 200 + 400
500+x=100+500
vay x =100
300-x=300+200
vay x= - 200
400-x=200+400
vay x= -200
Tính.
a) 200 mm + 100 mm 300 mm – 100 mm 200 mm x 3 600 mm : 3
b) 300 g + 200 g 200 g × 5 500 g – 300g 1000g : 5
c) 400 ml + 300 ml 800 ml : 4 700 ml – 300 ml 200 ml x 4
a) 200 mm + 100 mm = 300 mm 300 mm – 100 mm = 200 mm |
200 mm x 3 = 600 mm 600 mm : 3 = 200 mm |
b) 300 g + 200 g = 500 g | 200g x 5 = 1 000g | 500g – 300g = 200g | 1 000g : 5 = 200g |
c)
400 ml + 300 ml = 700 ml
800 ml : 4 = 200 ml
700 ml – 300 ml = 400 ml
200 ml x 4 = 800ml
Tìm x, biết
a) 70 - (x - 3) = 45; b) 12 + (5 + x) = 20
c) 130 - (100 + x) = 25; d)175 + (30 - x) = 200
e) (x + 12) + 22 = 92; f) 95 - (x + 2) = 45
a) \(70-\left(x-3\right)=45\)
\(x-3=70-45\)
\(x-3=25\)
\(x=25+3\)
\(x=28\)
b) \(12+\left(5+x\right)=20\)
\(5+x=20-12\)
\(5+x=8\)
\(x=8-5\)
\(x=3\)
c) \(130-\left(100+x\right)=25\)
\(100+x=130-25\)
\(100+x=105\)
\(x=105-100\)
\(x=5\)
d) \(175+\left(30-x\right)=200\)
\(30-x=200-175\)
\(30-x=25\)
\(x=30-25\)
\(x=5\)
e) \(\left(x+12\right)+22=92\)
\(x+12=92-22\)
\(x+12=70\)
\(x=70-12\)
\(x=58\)
f) \(95-\left(x+2\right)=45\)
\(x+2=95-45\)
\(x+2=50\)
\(x=50-2\)
\(x=48\)
a)
70 - (x - 3) = 45
x - 3 = 70 - 45 = 25
x = 25 + 3 = 28
Vậy x = 28
b)
12 + (5 + x) = 20
5 + x = 20 - 12 = 8
x = 8 - 5 = 3
Vậy x = 3
c)
130 - (100 + x) = 25
100 + x = 130 - 25 = 115
x = 115 - 100 = 15
Vậy x = 15
d)
175 + (30 - x) = 200
30 - x = 200 - 175 = 25
x = 30 - 25 = 5
Vậy x = 5
e)
(x + 12) + 22 = 92
x + 12 = 92 - 22 = 70
x = 70 - 12 = 58
Vậy x = 58
f)
95 - (x + 2) = 45
x + 2 = 95 - 45 = 50
x = 50 - 2 = 48
Vậy x = 48
Tính nhẩm (theo mẫu).
Mẫu: 200 x 2 = ? Nhẩm: 2 trăm x 2 = 4 trăm 200 x 2 = 400 |
300 x 3 200 x 4 400 x 2
300 x 3 Nhẩm: 3 trăm x 3 = 9 trăm 300 x 3 = 900 | 200 x 4 Nhẩm: 2 trăm x 4 = 8 trăm 200 x 4 = 800 | 400 x 2 Nhẩm: 4 trăm x 2 = 8 trăm 400 x 2 = 800 |
x-100=200+900
x+100=300-400
x - 100 = 200 + 900
x - 100 = 1100
x = 1100 + 100
x = 1200
x + 100 = 300 - 400
x + 100 = - 100
x = - 100 - 100
x = - 200
x+100=200+900
x+100=1000
x=1000-100
x=900
x+100=300-400
x+100=-100
x=-100-100
x=-200
X-100=200+900
X-100=1100
X =1100+100
X =1200