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a) 2205 : ( 35 x 7 ) 2205 : ( 35 x 7 )
= 2205 : 245 = 2205 : 35 : 7
= 9 = 63 : 7
= 9
b) 3332 : ( 4 x 49 ) 3332 : ( 4 x 49 )
= 3332 : 196 = 3332 : 4 : 49
= 17 = 833 : 49
= 17
a) 142 x 12 + 42 x 18 = 142 x (12 +18) = 142 x 30 = 4260
b) 49 x 365 – 39 x 365 = (49-39) x 365 = 10 x 365 = 3650
c) 4 x 18 x 25 = 18 x (4 x 25) = 10 x 100 = 1800
_k me_
@Min_ngu_ngục
_copy is not fun_
Tính bằng cách thuận tiện nhất :
a) 146 x 12 + 142 x 18
b) 49 x 365 - 39 x 365
c) 4 x 18 x 25
Bài giải
a) 142 x 12 + 142 x 18 = 142 x (12 + 18) = 142 x 30 = 4260
b) 49 x 365 – 39 x 365 = (49 – 39) x 365 = 10 x 365 = 3650
c) 4 x 18 x 25 = (4 x 25) x 18 = 100 x 18 = 1800
Chúc bạn học tốt nha!
a) 2205 : (35 x 7) = ?
Cách 1 : 2205 : (35 x 7) = 2205 : 245 = 9
Cách 2 : 2205 : (35 x 7) = 2205 : 35 : 7 = 63 : 7 = 9
b) 3332 : (4 x 49) = ?
Cách 1 : 3332 : (4 x 49) = 3332 : 196 = 17
Cách 2 : 3332 : (4 x 49) = = 3332 : 4 : 49 =833 : 49 = 17
Nói thêm: còn cách tính thứ ba nữa:
a. … = 2205 : 35 : 7 = 63 : 7 = 9
b. ….= 3332 : 49 : 4 = 68 : 4 = 17
1.
\(\frac{5}{3}-\frac{1}{4}+\frac{1}{3}-\frac{3}{4}\)
\(=\left(\frac{5}{3}+\frac{1}{3}\right)-\left(\frac{1}{4}+\frac{3}{4}\right)\)
\(=2-1=1\)
\(\frac{2}{7}\cdot\frac{1}{5}+\frac{2}{7}\cdot\frac{4}{5}=\frac{2}{7}\cdot\left(\frac{1}{5}+\frac{4}{5}\right)=\frac{2}{7}\cdot1=\frac{2}{7}\)
#Louis
\(1.a)\frac{5}{3}-\frac{1}{4}+\frac{1}{3}-\frac{3}{4}\)
\(=\left(\frac{5}{3}+\frac{1}{3}\right)-\left(\frac{1}{4}+\frac{3}{4}\right)\)
\(=2-1\)
\(=1\)
\(b)\frac{2}{7}\times\frac{1}{5}+\frac{2}{7}\times\frac{4}{5}\)
\(=\frac{2}{7}\times\left(\frac{1}{5}+\frac{4}{5}\right)\)
\(=\frac{2}{7}\times1\)
\(=\frac{2}{7}\)
\(2.a)\frac{5}{6}+\frac{7}{12}-\frac{2}{9}\)
\(=\frac{30}{36}+\frac{21}{36}-\frac{8}{36}\)
\(=\frac{43}{36}\)
\(b)\frac{4}{9}\times\frac{5}{8}+\frac{1}{6}\)
\(=\frac{5}{18}+\frac{1}{6}=\frac{5}{18}+\frac{3}{18}\)
\(=\frac{8}{18}=\frac{4}{9}\)
\(c)2:\frac{3}{11}-\frac{13}{12}\)
\(=2\times\frac{11}{3}-\frac{13}{12}\)
\(=\frac{22}{3}-\frac{13}{12}\)
\(=\frac{25}{4}\)
Bài 1:
\(\dfrac{2}{3}\) + \(\dfrac{3}{4}\) - \(\dfrac{2}{5}\)
=\(\dfrac{40}{60}\) + \(\dfrac{45}{60}\) - \(\dfrac{24}{60}\)
= \(\dfrac{61}{60}\)
b; \(\dfrac{12}{13}\) x \(\dfrac{3}{4}\) - \(\dfrac{7}{13}\)
= \(\dfrac{9}{13}\) - \(\dfrac{7}{13}\)
= \(\dfrac{2}{13}\)
c; \(\dfrac{15}{17}\) : \(\dfrac{19}{34}\) - \(\dfrac{17}{19}\)
= \(\dfrac{15}{17}\) x \(\dfrac{34}{19}\) - \(\dfrac{17}{19}\)
= \(\dfrac{30}{19}\) - \(\dfrac{17}{19}\)
= \(\dfrac{13}{19}\)
Bài 2:
a; \(\dfrac{x}{5}\) x \(\dfrac{3}{7}\) = \(\dfrac{9}{35}\)
\(\dfrac{x}{5}\) = \(\dfrac{9}{35}\) : \(\dfrac{3}{7}\)
\(\dfrac{x}{5}\) = \(\dfrac{3}{5}\)
\(x\) = \(\dfrac{3}{5}\) x 5
\(x\) = 3
a, 8 x 6/32 x 1/5 = 3/10
8 x 6/32 x 1/5 = 8 x 3/16 x 1/5 = 3/10
b, 15/16 x 36/35 x 28 = 27
Tính bằng 2 cách :
a). 234 x 25 + 234 x 75
C1: \(234\times25+234\times75\)
\(=5850+17550\)
\(=23400\)
C2: \(234\times25+234\times75\)
\(=234\times\left(25+75\right)\)
\(=234\times100\)
\(=23400\)
b). 765 x 123 - 755 x 23
C1: \(765\times123-765\times23\)
\(=94095-17595\)
\(=76500\)
C2: \(765\times123-765\times23\)
\(=765\times\left(123-23\right)\)
\(=765\times100\)
\(=76500\)
=> Bạn xem lại đề ạ!
c). 476 x ( 45 + 55 )
C1: \(476\times\left(45+55\right)\)
\(=476\times100\)
\(=47600\)
C2: \(476\times\left(45+55\right)\)
\(=476\times45+476\times55\)
\(=21420+26180\)
\(=47600\)
d). 2415 : 5 : 5
=> Xem lại đề ạ
e). ( 76 x 28 ) : 7
C1: \(\left(76\times28\right)\div7\)
\(=2128\div7\)
\(=304\)
C2: \(\left(76\times28\right)\div7\)
\(=76\times\left(28\div7\right)\)
\(=76\times4\)
\(=304\)
g). ( 175 + 29070 ) : 5
C1: \(\left(175+29070\right)\div5\)
\(=29245\div5\)
\(=5849\)
C2: \(\left(175+29070\right)\div5\)
\(=175\div5+29070\div5\)
\(=35+5814\)
\(=5849\)
h). ( 3224 - 1236 ) : 4
C1: \(\left(3224-1236\right)\div4\)
\(=1988\div4\)
\(=497\)
C2: \(\left(3224-1236\right)\div4\)
\(=3224\div4-1236\div4\)
\(=806-309\)
\(=497\)
a,
c1: 2205:245=9
c2: 2205:35:7=9
b,
c1: 3332:196=17
c1: 3332:4:49=17
a) 2205 :(35 x 7)
C1: = 2205:35:7
=63:7
=9
C2: =2205:245
=9
b, 3332:(4x49)
C1:= 3332:196
=17
C2: = 3332:4:49
=833:49
=17