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c1
a,3/15 = 3:3/15:3 = 15
33/44 = 33:11/44:11 = 34
2/8 = 2:2/8:2 = 1/4
b,9/12 =9:3/12:3 = 34
24/36 =24:12/36:12 = 23
3/8 = 3:1/8:1 = 3/8
c2
a) =12x(4+6)/24
= 12x10/24
=120/24
=5
b,16x8-16x2/12x4
=16x(8-2)/48
=16x6/48
=2
c3
5/8=45/72
20/15=4/3=96/72
24/32=3/4=54/72
15/18=5/6=60/72
77/99=7/9=56/72
c4
2/3=2/3
12/15=4/5
24/18=4/3
16/48=1/3
75/100=3/4
30/45=2/3
12/36=1/3
20/15=4/3
các phân số lớn hơn 1 luôn có mẫu số bé hơn tử số
vậy các số lớn hơn 1 là 24/18,20/15
k mk nha thank mọi ng'
a, \(\frac{3}{15}=\frac{1}{5}=\frac{4}{20}\); \(\frac{33}{44}=\frac{3}{4}=\frac{15}{20}\); \(\frac{2}{8}=\frac{1}{4}=\frac{5}{20}\)
b, \(\frac{9}{12}=\frac{3}{4}=\frac{18}{24}\); \(\frac{24}{36}=\frac{2}{3}=\frac{16}{24}\); \(\frac{3}{8}=\frac{9}{24}\)
Bài 2 :
a,\(\frac{12x4+12x6}{24}=\frac{12x\left(4+6\right)}{24}=\frac{1x10}{2}=\frac{10}{2}=\frac{5}{1}\)
b, \(\frac{16x8-16x2}{12}=\frac{16x\left(8-2\right)}{12}=\frac{8x6}{6}=\frac{8}{1}\)
Tính nhanh mỗi biểu thức sau:
a, 0 + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 + 14 + 15 + 16 + 17 + 18 + 19 + 20
= (0 + 20) + (1 + 19) + (2 + 18) + (3 + 17) + (4 + 16) + (5 + 15) + (6 + 14) + (7 + 13) + (8 + 12) + (9 + 11) + 10
= 20 + 20 + 20 + 20 + 20 + 20 + 20 + 20 + 20 + 20 + 10
= 20 x 10 + 10
= 200 + 10
= 210
b, 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x (4 x 9 - 36)
= 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x (36 - 36)
= 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x 0
= A x 0
= 0
c, (81 - 7 x 9 - 18) : (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9)
= (81 - 63 - 18) : (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9)
= (18 - 18) : (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9)
= 0 :(1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9)
= 0 : A
= 0
d, (6 x 5 + 7 - 37) x (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)
= (30 + 7 - 37) x (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)
= (37 - 37) x (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)
= 0 x (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)
= 0 x A
= 0
e, (11 x 9 - 100 + 1) : (1 x 2 x 3 x 4 x ... x 10)
= (99 - 100 + 1) : (1 x 2 x 3 x 4 x ... x 10)
= (99 + 1 - 100) : (1 x 2 x 3 x 4 x ... x 10)
= (100 - 100) : (1 x 2 x 3 x 4 x ... x 10)
= 0 : (1 x 2 x 3 x 4 x ... x 10)
= 0 : A
= 0
g, (m : 1 - m x 1) : (m x 2008 + m x 2008)
= (m - m) : (m x 2008 + m x 2008)
= 0 : (m x 2008 + m x 2008)
= 0 : A
= 0
h, (2 + 4 + 6 + 8 + m x n) x (324 x 3 - 972)
= (2 + 4 + 6 + 8 + m x n) x (972 - 972)
= (2 + 4 + 6 + 8 + m x n) x 0
= A x 0
= 0
l, (1 + 2 + 3 + ... + 99) x (13 x 15 - 12 x 15 - 15)
= (1 + 2 + 3 + ... + 99) x (15 x (13 - 12 - 1))
= (1 + 2 + 3 + ... + 99) x (15 x 0)
= (1 + 2 + 3 + ... + 99) x 0
= A x 0
= 0
i, (0 x 1 x 2 x...x 99 x 100) : (2 + 4 + 6 +...+ 98)
= 0 x : (2 + 4 + 6 +...+ 98)
= 0 x A
= 0
k, (0 + 1 + 2 +...+ 97 + 99) x (45 x 3 - 45 x 2 - 45)
= (0 + 1 + 2 +...+ 97 + 99) x (45 x (3 - 2 - 4))
= (0 + 1 + 2 +...+ 97 + 99) x (45 x 0)
= (0 + 1 + 2 +...+ 97 + 99) x 0
= A x 0
= 0
Bài 1:
Rút gọn các phân số sau:
\(\dfrac{12}{24}\) = \(\dfrac{12:12}{24:12}\) = \(\dfrac{1}{2}\)
\(\dfrac{120}{90}\) = \(\dfrac{120:30}{90:30}\) = \(\dfrac{4}{3}\)
\(\dfrac{42}{24}\) = \(\dfrac{42:6}{24:6}\) = \(\dfrac{7}{4}\)
Bài 2:
Tính bằng cách thuận tiện:
\(\dfrac{13}{19}\) + \(\dfrac{18}{19}\) + \(\dfrac{17}{19}\)
= \(\dfrac{13+18+17}{19}\)
= \(\dfrac{\left(13+17\right)+18}{19}\)
= \(\dfrac{48}{19}\)
\(\dfrac{12}{17}\) + \(\dfrac{19}{17}\) + \(\dfrac{8}{17}\)
= \(\dfrac{12+19+8}{17}\)
= \(\dfrac{\left(12+8\right)+19}{17}\)
= \(\dfrac{39}{17}\)
A) \(\frac{7}{8}-\frac{5}{12}=\frac{84}{96}-\frac{40}{96}=\frac{44}{96}=\frac{11}{24}\)
B)\(\frac{8}{15}-\frac{2}{5}=\frac{8}{15}-\frac{6}{15}=\frac{2}{15}\)
C)\(\frac{5}{6}-\frac{3}{10}=\frac{50}{60}-\frac{18}{60}=\frac{32}{60}=\frac{8}{15}\)
D)\(\frac{7}{10}-\frac{1}{5}=\frac{7}{10}-\frac{2}{10}=\frac{5}{10}=\frac{1}{2}\)
2)A)\(\frac{5}{10}-\frac{2}{15}=\frac{1}{2}-\frac{2}{15}=\frac{15}{30}-\frac{4}{30}=\frac{11}{30}\)
B)\(\frac{5}{20}-\frac{1}{6}=\frac{1}{4}-\frac{1}{6}=\frac{6}{24}-\frac{4}{24}=\frac{2}{24}=\frac{1}{12}\)
C)\(\frac{6}{18}-\frac{6}{24}=\frac{1}{3}-\frac{1}{4}=\frac{4}{12}-\frac{3}{12}=\frac{1}{12}\)
D)\(\frac{5}{9}-\frac{3}{12}=\frac{5}{9}-\frac{1}{4}=\frac{20}{36}-\frac{9}{36}=\frac{11}{36}\)
Chúc bạn học tốt
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19
=(1+19)+(2+18)+(3+17)+(4+16)+(5+15)+(6+14)+(7+13)+(8+12)+(9+11)+10
=20+20+20+20+20+20+20+20+20+10
=20×9+10
=180+10
=190
Nay rảnh lại qua làm mấy bài lớp 4 ^^
Tui làm luôn kh ghi đề nhá
1,
\(\frac{2}{3}+\frac{8}{15}=\frac{6}{5}\)
\(\frac{2}{5}+\frac{2}{3}=\frac{16}{15}\)
\(\frac{2}{3}+\frac{5}{6}=\frac{3}{2}\)
2,
\(\cdot\frac{3}{7}+\frac{6}{5}+\frac{4}{7}\)
\(=\frac{3}{7}+\frac{4}{7}+\frac{6}{5}\)
\(=1+\frac{6}{5}\)
\(=\frac{11}{5}\)
\(\cdot\frac{6}{4}+\frac{7}{3}+\frac{4}{4}+\frac{3}{3}\)
\(=\frac{6}{4}+\frac{4}{4}+\frac{7}{3}+\frac{3}{3}\)
\(=\frac{10}{4}+\frac{10}{3}\)
\(=\frac{35}{6}\)
23+815=6523+815=65
25+23=161525+23=1615
23+56=3223+56=32
2,
⋅37+65+47⋅37+65+47
=37+47+65=37+47+65
=1+65=1+65
=115=115
⋅64+73+44+33⋅64+73+44+33
=64+44+73+33=64+44+73+33
=104+103=104+103
=356
a) = 13/12
b) = 5/9
c) = 1/9
d) = 1/12
e) = 11/24
học tốt nha e
7/8 - 3/4 = 1/8
5/6 - 5/8 = 5/24
19/36 - 3/12 = 5/18
12/24 - 6/18 = 1/6
99/72 - 15/40 - 1212/1616 = 1/4
k nhé:))
a. 1/8
b. 5/24
c.5/19
d.1/6
e/1/4
HT