a) 4/9.(5/7+2/5).4/9.(-2)/7+7/5
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H9
HT.Phong (9A5)
CTVHS
2 tháng 11 2023
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) \(362\times728+326\times272\)
\(=326\times\left(728+272\right)\)
\(=326\times1000\)
\(=326000\)
CM
24 tháng 1 2018
Phương pháp giải:
Tính nhẩm rồi điền kết quả vào chỗ trống.
Lời giải chi tiết:
a)
7 + 5 = 12 5 + 7 = 12
4 + 9 = 13 9 + 4 = 13
8 + 7 = 15 7 + 8 = 15
2 + 9 = 11 9 + 2 = 11
b)
16 − 8 = 8 14 − 7 = 7
11 − 9 = 2 17 − 9 = 8
12 − 5 = 7 16 − 9 = 7
13 − 6 = 7 15 − 8 = 7
19 tháng 12 2022
\(9+2+5+3+7+8+4+2+9+6+4+65+6+7+4+6+3+7+4+8+5+9+08+87+1+2+3+4+2+3+2+5+6+767+5+75+6+4+6+5+66+5+7+546+46+43+6+3+6+4+6+7+8878+68+68+6+7+9+9=10961\)
KV
4 tháng 12 2023
a) 1/2 + 3/4 - (3/4 - 4 - 5)
= 1/2 + 3/4 - 3/4 + 4 + 5
= (3/4 - 3/4) + (4 + 5) + 1/2
= 0 + 9 + 1/2
= 19/2
b) [9/16 + 8/(-27)] - (19/27- 7/16 - 2)
= 9/16 - 8/27 - 19/27 + 7/16 + 2
= (9/16 + 7/16) + (-8/27 - 19/27) + 2
= 1 - 1 + 2
= 2
c) -5/8 . [4/9 + 7/(-12)]
= -5/8 . (-5/36)
= 25/288
d) 7/10 . (-3/5) + 7/10 . (-2/5) - (-3/10)
= 7/10 . (-3/5 - 2/5) + 3/10
= 7/10 . (-1) + 3/10
= -2/5
e) -3/7 . 5/9 + 4/9 . (-3/7) + 2 3/7
= -3/7 . (5/9 + 4/9) + 17/7
= -3/7 . 1 + 17/7
= 2
f) 8 2/7 - (3 4/9 + 4 2/7)
= 8 + 2/7 - 3 - 4/9 - 4 - 2/7
= (8 - 3 - 4) + (2/7 - 2/7) - 4/9
= 1 - 4/9
= 5/9
h) 3.(-1/2)² - (4/5 + 8/15) : 5/6
= 3.1/4 - 4/3 : 5/6
= 3/4 - 8/5
= -17/20
TN
3 tháng 1 2022
7)=-5.(-1)-7.2
=5-14
=-9
8)=7.(-2) - 9.(-5)
= -14-(-45)
=31
9)= -8.(-1)+7.4
=8+28
=36
10)= -2.(-2)+4.2
=4+8
=12
a) \(\frac{4}{9}.\left(\frac{5}{7}+\frac{2}{5}\right).\frac{4}{9}.\frac{-2}{7}+\frac{7}{5}\)
= \(\frac{4}{9}.\left(\frac{25}{35}+\frac{14}{35}\right).\frac{-8}{63}+\frac{7}{5}\)
= \(\frac{4}{9}.\frac{39}{35}.\frac{-8}{63}+\frac{7}{5}\)
= \(\frac{4.39.\left(-8\right)}{9.35.63}+\frac{7}{5}\)
= \(\frac{-416}{6615}+\frac{7}{5}\)
= \(\frac{-416}{6615}+\frac{9261}{6615}\)
= \(\frac{8845}{6615}\)
= \(\frac{1769}{1323}\)