Tính nhẩm.
a) 9 x 1 9 x 4 9 x 7
b) 9 x 2 9 x 5 9 x 8
c) 9 x 3 9 x 6 9 x 9
d) 9 x 10 9 x 0 0 x 9
Tính bằng cách thuận tiện
a. 5/7 x 5/9 + 4/9 x 5/7
b. 1/10 + 5/9 + 4/9 + 9/10 – 1
c. 5/7 x 5/9 + 4/9 x 5/7 + 2/7
d. 2/7 + 2/8 + 1/4 + 1/7 + 4/7
e. 4/5 + 3/10 + 2/10 + 0,7
f. 326 x 728 + 326 x 272
a) \(\dfrac{5}{7}\times\dfrac{5}{9}+\dfrac{4}{9}\times\dfrac{5}{7}\)
\(=\dfrac{5}{7}\times\left(\dfrac{4}{9}+\dfrac{5}{9}\right)\)
\(=\dfrac{5}{7}\times1\)
\(=\dfrac{5}{7}\)
b) \(\dfrac{1}{10}+\dfrac{5}{9}+\dfrac{4}{9}+\dfrac{9}{10}-1\)
\(=\left(\dfrac{5}{9}+\dfrac{4}{9}\right)+\left(\dfrac{1}{10}+\dfrac{9}{10}-1\right)\)
\(=1+0\)
\(=1\)
c) \(\dfrac{5}{7}\times\dfrac{5}{9}+\dfrac{4}{9}\times\dfrac{5}{7}+\dfrac{2}{7}\)
\(=\dfrac{5}{7}\times\left(\dfrac{5}{9}+\dfrac{4}{9}\right)+\dfrac{2}{7}\)
\(=\dfrac{5}{7}+\dfrac{2}{7}\)
\(=1\)
d) \(\dfrac{2}{7}+\dfrac{2}{8}+\dfrac{1}{4}+\dfrac{1}{7}+\dfrac{4}{7}\)
\(=\left(\dfrac{2}{8}+\dfrac{1}{4}\right)+\left(\dfrac{2}{7}+\dfrac{1}{7}+\dfrac{4}{7}\right)\)
\(=\left(\dfrac{1}{4}+\dfrac{1}{4}\right)+1\)
\(=\dfrac{1}{2}+1\)
\(=\dfrac{3}{2}\)
e) \(\dfrac{4}{5}+\dfrac{3}{10}+\dfrac{2}{10}+0,7\)
\(=\dfrac{4}{5}+\dfrac{5}{10}+\dfrac{7}{10}\)
\(=\dfrac{4}{5}+\dfrac{12}{10}\)
\(=\dfrac{4}{5}+\dfrac{6}{5}\)
\(=\dfrac{10}{5}\)
\(=2\)
g) \(362\times728+326\times272\)
\(=326\times\left(728+272\right)\)
\(=326\times1000\)
\(=326000\)
Tính nhẩm
9 x 1 = ..... 9 x 3 = ..... 9 x 5 = ..... 9 x 7 = ..... 9 x 9 = .....
9 x 2 = ..... 9 x 4 = ..... 9 x 6 = ..... 9 x 8 = ..... 9 x 10 = .....
9 x 1 = 9 9 x 3 = 27 9 x 5 = 45 9 x 7 = 63 9 x 9 = 81
9 x 2 = 18 9 x 4 = 36 9 x 6 = 54 9 x 8 = 72 9 x 10 = 90
Tính nhẩm :
9 x 1 =
9 x 5 =
9 x 4 =
9 x 10 =
9 x 2 =
9 x 7 =
9 x 8 =
9 x 0 =
9 x 3 =
9 x 9 =
9 x 6 =
0 x 9 =
9 x 1 = 9
9 x 5 = 45
9 x 4 = 32
9 x 10 = 90
9 x 2 = 18
9 x 7 = 63
9 x 8 = 72
9 x 0 = 0
9 x 3 = 27
9 x 9 = 81
9 x 6 = 54
0 x 9 = 0
= 9 = 45 = 36
Tính nhẩm :
9 x 4 =
9 x 2 =
9 x 5 =
9 x 10 =
9 x 1 =
9 x 7 =
9 x 8 =
0 x 9 =
9 x 3 =
9 x 6 =
9 x 9 =
9 x 0 =
9 x 4 = 36
9 x 2 = 18
9 x 5 = 40
9 x 10 = 90
9 x 1 = 9
9 x 7 = 63
9 x 8 = 72
0 x 9 = 0
9 x 3 = 27
9 x 6 = 54
9 x 9 = 81
9 x 0 = 0
Tính nhẩm
9 x 1 = ..... | 9 x 2 = ..... | 9 x 3 = ..... | 9 x 4 = ..... |
1 x 9 = ..... | 2 x 9 = ..... | 3 x 9 = ..... | 4 x 9 = ..... |
9 x 5 = ..... | 9 x 6 = ..... | 9 x 7 = ..... | 9 x 8 = ..... |
5 x 9 = ..... | 6 x 9 = ..... | 7 x 9 = ..... | 8 x 9 = ..... |
9 x 1 = 9 | 9 x 2 = 18 | 9 x 3 = 27 | 9 x 4 = 36 |
1 x 9 = 9 | 2 x 9 = 18 | 3 x 9 = 27 | 4 x 9 = 36 |
9 x 5 = 45 | 9 x 6 = 54 | 9 x 7 = 63 | 9 x 8 = 72 |
5 x 9 = 45 | 6 x 9 = 54 | 7 x 9 = 63 | 8 x 9 =72 |
Tính nhanh các biểu thức sau :
a) (45 – 5 x 9) x 1 x 2 x 3 x 4 x 5 x 6 x 7
b) (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x (72 – 8 x 8 – 8)
c) (36 – 4 x 9) : (3 x 5 x 7 x 9 x 11)
d) (27 – 3 x 9) : 9 x 1 x 3 x 5 x 7
Ta có:
a) ( 45 – 5 x 9 ) x 1 x 2 x 3 x 4 x 5 x 6 x 7
= (45 – 45) x 1 x 2 x 3 x 4 x 5 x 6 x 7
= 0 x 1 x 2 x 3 x 4 x 5 x 6 x 7
= 0
b) (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x (72 – 8 x 8 – 8)
= (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x (72 – 64 – 8)
= (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x 0
= 0
c) (36 – 4 x 9) : (3 x 5 x 7 x 9 x 11)
= (36 – 36) : (3 x 5 x 7 x 9 x 11)
= 0 : (3 x 5 x 7 x 9 x 11)
= 0
d) (27 – 3 x 9) : 9 x 1 x 3 x 5 x 7
= (27 – 27) : 9 x 1 x 3 x 5 x 7
= 0 : 9 x 1 x 3 x 5 x 7
=0
a) ( 45 – 5 x 9 ) x 1 x 2 x 3 x 4 x 5 x 6 x 7
= 0 x 1 x 2 x 3 x 4 x 5 x 6 x 7
b) (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x (72 – 8 x 8 – 8)
= (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x 0
c) (36 – 4 x 9) : (3 x 5 x 7 x 9 x 11)
= 0 : (3 x 5 x 7 x 9 x 11)
d) (27 – 3 x 9) : 9 x 1 x 3 x 5 x 7
= 0 : 9 x 1 x 3 x 5 x 7 Nếu đúng thì k cho mình nhé bạn!
a. ( 45 – 5 x 9 ) x 1 x 2 x 3 x 4 x 5 x 6 x 7
= (45 – 45) x 1 x 2 x 3 x 4 x 5 x 6 x 7
= 0 x 1 x 2 x 3 x 4 x 5 x 6 x 7
= 0
b. (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x (72 – 8 x 8 – 8)
= (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x (72 – 64 – 8)
= (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) x 0
= 0
c. (36 – 4 x 9) : (3 x 5 x 7 x 9 x 11)
= (36 – 36) : (3 x 5 x 7 x 9 x 11)
= 0 : (3 x 5 x 7 x 9 x 11)
= 0
d. (27 – 3 x 9) : 9 x 1 x 3 x 5 x 7
= (27 – 27) : 9 x 1 x 3 x 5 x 7
= 0 : 9 x 1 x 3 x 5 x 7
=0
1. -2/9 x 15/17 + -2/9 x 2/17
2. -5/3 x 6/5 + -7/9 x 3/10
3. 15/20 x 7/5 + -9/7 x -6/4
4.-25/13 x 5/19 + -25/13 x 14/19
5 -7/13 x 13/5 + -9/7 x 5/3
6. 27/35 x 5/9 - 2/7 x -7/5
7. 10/13 x 13/5 + {-9/5} x 10/3
8. 100/27 x 9/20 + 40% x 5/3
9. 1,5 x 5/12 + 1/4 x 3/4
10. 2 1/2 x 7/5 + {-9/10} x 2/3
11. X + 45% = 2 1/2 -5/3
12. 80% + X = -5/2 + 3/4
13. 4/25 - X =-5/2 + -3/10
1: =-2/9(15/17+2/17)=-2/9
2: \(=\dfrac{-6}{3}+\dfrac{-21}{90}\)
=-2-7/30=-67/30
3: \(=\dfrac{3}{4}\cdot\dfrac{7}{5}+\dfrac{9}{7}\cdot\dfrac{3}{2}\)
=21/20+27/14=417/140
4: =-25/13(5/19+14/19)=-25/13
5: =-7/5-45/21=-7/5-15/7=-124/35
1: =-2/9(15/17+2/17)=-2/9
2: =34⋅75+97⋅32=34⋅75+97⋅32
=21/20+27/14=417/140
4: =-25/13(5/19+14/19)=-25/13
5: =-7/5-45/21=-7/5-15/7=-124/35
Tính nhẩm
9 x 2 = ...... | 9 x 3 = ...... | 9 x 4 = ...... | 9 x 5 = ...... |
18 : 9 = ...... | 27 : 9 = ...... | 36 : 9 = ...... | 45 : 9 = ...... |
9 x 6 = ...... | 9 x 7 = ...... | 9 x 8 = ...... | 9 x 9 = ...... |
54 : 9 = ...... | 63 : 9 = ...... | 72 : 9 = ...... | 81 : 9 = ...... |
9 x 2 = 18 | 9 x 3 = 27 | 9 x 4 = 36 | 9 x 5 = 45 |
18 : 9 = 2 | 27 : 9 = 3 | 36 : 9 = 4 | 45 : 9 = 5 |
9 x 6 = 54 | 9 x 7 = 63 | 9 x 8 = 72 | 9 x 9 = 81 |
54 : 9 = 6 | 63 : 9 = 7 | 72 : 9 = 8 | 81 : 9 = 9 |
9 x 2 = 18 9 x 3 = 27 9 x 4 = 36 9 x 5 = 45
18 : 9 = 2 27 : 9 = 3 36 : 9 = 4 45 : 9 = 5
9 x 6 = 54 9 x 7 = 63 9 x 8 = 72 9 x 9 = 81
54 : 9 = 6 63 : 9 = 7 72 : 9 = 8 81 : 9 = 9
9 x 1 =
9 x 2 =
9 x 3 =
9 x 4 =
9 x 5 =
9 x 6 =
9 x 7 =
9 x 8 =
9 x 9 =
9 x 10 =
9x1=9
9x2=18
9x3=27
9x4=36
9x5=45
9x6=54
9x7=63
9x8=72
9x10=90
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