a, 49 + 28 = ? c, 17 + 36 = ?
b, 43+ 12 = ? d, 51 + 76 = ?
Đặt tính rồi tính:
a) 36 + 36
b) 55 + 25
c) 17 + 28
d) 76 - 13
1.
a, |-15+6 |
b, |-25+(-17) |
c, |-36+15 |
d, |-21+49 |
e, |-21+49 |
g, |43+(-28) |
h, |-23+33 |
i, |-46+(-29) |
a) |-15+6| = |-9| = 9
b) |-25 + (-17)| = |-42| = 42
c) | -36 + 15| = |-21| = 21
d) |-21 + 49| = | 48| = 48
e) |-21+49| = |48| = 48
g) |43 + (-28) | = | 15| = 15
h) |-23 + 33| = |10| = 10
i) |-46 + (-29) | = | -75| = 75
a) 9/22 x 33/18 =
b) 12/35 : 36/25 =
c) 19/17 : 76/51 =
a) 9/22 x 33/18 =3/4
b) 12/35 : 36/25 = 5/21
c) 19/17 : 76/51 =3/4
a) \(\frac{9}{22}\times\frac{33}{18}\)
\(=\frac{9}{22}\times\frac{11}{6}\)
\(=\frac{9\times11}{22\times6}=\frac{3}{4}\)
b) \(\frac{12}{35}:\frac{36}{25}=\frac{12}{35}\times\frac{25}{36}\)
\(=\frac{5}{21}\)
c) \(\frac{19}{17}:\frac{76}{51}=\frac{19}{17}\times\frac{51}{76}\)
\(=\frac{3}{4}\)
\(a,\frac{9}{22}x\frac{33}{18}\)
\(=\frac{3.3.11.3}{11.2.3.3.2}\)
\(=\frac{3}{2.2}\)
\(=\frac{3}{4}\)
\(b,\frac{12}{35}:\frac{36}{25}\)
\(=\frac{12}{35}.\frac{25}{36}\)
\(=\frac{12.25}{35.36}\)
\(=\frac{12.5.5}{5.7.12.3}\)
\(=\frac{5}{7.3}\)
\(=\frac{5}{21}\)
\(c,\frac{19}{17}:\frac{76}{51}\)
\(=\frac{19}{17}.\frac{51}{76}\)
\(=\frac{19.51}{17.76}\)
\(=\frac{19.17.3}{17.19.4}\)
\(=\frac{3}{4}\)
Tính số phần tử của các tập hợp sau:
a) A = 15 ; 17 ; 19 ; . . . . . ; 49 ; 51 ;
b) B = 10 ; 12 ; 14 ; . . . . ; 76 ; 78
1. Tính nhanh:
a, 36 . 23 + 62 . 23 + 46
b, 3 . 8 . 76 + 2 . 35 . 12 - 4 . 11 . 6
c, 64 . 23 + 37 . 23 - 23
d, 43 . 11
e, 67 . 99
2. So sánh:
A = 200 . 200 và B = 199 . 201
3. Tìm x:
a, (46 . 51 - x) + 20,57 = 62,4
b, 2018 . x - 2018 = 0
c, x . (x -1) = 0
d, (x + 17) : 4 + 24 = 29
e, 1/5 . 6 + 1/6 . 7 + .......... + 1/49 . x = 1/10
Bài 1.Tính
a)\(\dfrac{4}{28}\)+\(\dfrac{12}{36}\) b)\(\dfrac{-12}{18}\)+\(\dfrac{15}{-21}\) c)\(\dfrac{14}{28}\)-\(\dfrac{-16}{32}\)-\(\dfrac{17}{51}\)
\(a,\dfrac{1}{7}+\dfrac{1}{3}=\dfrac{3}{21}+\dfrac{7}{21}=\dfrac{10}{21}\\ b,\dfrac{-2}{3}+\dfrac{-5}{7}=\dfrac{-14+\left(-15\right)}{21}=\dfrac{-29}{21}\\ c,\dfrac{1}{2}-\dfrac{-1}{2}-\dfrac{1}{3}=\dfrac{3+3-2}{6}=\dfrac{4}{6}=\dfrac{2}{3}\)
\(a.\dfrac{4}{28}+\dfrac{12}{36}=\dfrac{1}{7}+\dfrac{1}{3}=\dfrac{3}{21}+\dfrac{7}{21}=\dfrac{10}{21}\\ b.\dfrac{-12}{18}+\dfrac{-15}{21}=\dfrac{-2}{3}+\dfrac{-5}{7}=\dfrac{-14}{21}+\dfrac{-15}{21}=\dfrac{-29}{21}\\ c.\dfrac{14}{28}+\dfrac{16}{32}-\dfrac{17}{51}=\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{17}{51}=1-\dfrac{17}{51}=\dfrac{2}{3}\)
\(\dfrac{4}{28}+\dfrac{12}{36}=\dfrac{144}{1008}+\dfrac{336}{1008}=\\ \dfrac{480}{1008}=\dfrac{10}{21}\)
Câu b và c em làm tương tự.
Tính:
a) (-12) + 25 + 75 + 12;
b) 60 + 12 + ( - 17) + ( - 43);
c) (-2)+ (-87)+ (-18)+ 87;
d) ( -1) + (-2) + 36 + (-17).
a) (-12) + 25 + 75 + 12 = (-12) + 12 + 25 + 75 = 0 +100 = 100.
b) 60 +12 + (-17) + (-43) = 60 + [(-47) + (-43)] +12.
c) (-2) + (-87) + (-18) + 87 = [(-2) + (-18)] + [(-87) + 87].
d) (-1)+(-2) + 36 + (-17) = 36+[(-1) + (-2) + (-17)].
a, (-12) + 25 + 75 + 12
= [ (-12) + 12] + (25 + 75)
= 0 + 100
= 100
b, 60 + 12 + (-17) + (-43)
= -(17 + 43) + 60 + 12
= - 60 + 60 + 12
= 0 + 12
= 12
Tính:. a) (-12) + 25 + 75 + 12; b) 60 + 12 + ( - 17) + ( - 43) c) (-2)+ (-87)+ (-18)+ 87; d) ( -1) + (-2) + 36 + (-17)
Tính nhanh.
a) 2459 - (400 + 459)
b) 435 nhân 25 + 76 nhân 435 - 435
c) 36 nhân 49 + 51 nhân 36
a) 2459 - ( 400 + 459 )
= 2459 - 400 - 459
= 2000 - 400
= 1600
b) 435 x 25 +76 x 435 - 435
= 435 x 25 + 76 x 435 - 435 x 1
= 435 ( 25 + 76 - 1 )
= 435 x 100
= 43500
c) 36 x 49 + 51 x 36
= 36 ( 49 + 51 )
= 36 x 100
= 3600
sao câu nào Ngọc Nguyễn Minh cũng được l-i-k-e thế
a) 2459 - ( 400 + 459 )
= 2459 - 400 - 459
= (2459 - 459 ) - 400
= 2000 - 400
= 1600 (L~I~K~E)
Cái * là nhân
b) 435 * 25 +76 * 435 - 435
= 435 *25 +76 * 435 - 435 * 1
= 435 * ( 25 + 76 - 1 )
= 435 * ( 101 -1 )
= 435 * 100
= 43500 (L~I~K~E)
c) 36 * 49 + 51 * 36
= 36 * ( 49 + 51 )
= 36 * 100
= 3600 (L~I~K~E)