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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!
1.
a. = 135 x ( 6 + 4 )
= 135 x 10
= 1350
b. = 432 x (4 + 3 + 2 + 1)
= 432 x 10
= 4320
2.
a. X x (2 + 3 + 4) = 234
X x 9 = 234
X = 234 : 9
X = 26
b. X x (1 + 2) = 12
X x 3 = 12
X = 12 : 3
X = 4
c. X x (1 + 3 + 5) = 135
X x 9 = 135
X = 135 : 9
X = 15
A)135x(4+6)=135x10=1350
B)432x(4+3+2+1)=432x10=4320
A)Xx(2+3+4)=234
Xx9=234
X=36
a) \(x-\frac{4}{9}=\frac{5}{6}\)
\(\Leftrightarrow\frac{18x}{18}-\frac{8}{18}=\frac{15}{18}\)
\(\Rightarrow18x-8=15\)
\(\Leftrightarrow18x=15+8\)
\(\Leftrightarrow18x=23\)
\(\Leftrightarrow x=\frac{23}{18}\)
Vậy \(x=\frac{23}{18}\)
b)\(x-7=\frac{1}{6}\)
\(\Leftrightarrow\frac{6x}{6}-\frac{42}{6}=\frac{1}{6}\)
\(\Rightarrow6x-42=1\)
\(\Leftrightarrow6x=42+1\)
\(\Leftrightarrow6x=43\)
\(\Leftrightarrow x=\frac{43}{6}\)
Vậy \(x=\frac{43}{6}\)
c)\(x-\frac{7}{8}=11\)
\(\Leftrightarrow\frac{8x}{8}-\frac{7}{8}=\frac{88}{8}\)
\(\Rightarrow8x-7=88\)
\(\Leftrightarrow8x=88+7\)
\(\Leftrightarrow8x=95\)
\(\Leftrightarrow x=\frac{95}{8}\)
Vậy \(x=\frac{95}{8}\)
#bn cs thể bỏ\(\Leftrightarrow;\Rightarrow\)đều đc nhé #
#hoktot<3#
a, x - 4/9 = 5/6
x = 5/6 + 4/9
x = 69/54
b, x - 7 = 1/6
x = 1/6 + 7
x = 43/6
c, x - 7/8 = 11
x = 11 + 7/8
x = 95/8
b, 3/5 + 4/7 + 2/8 + 10/25 + 9/21 + 28/16
= 3/5 + 4/7 + 2/8 + 2/5 + 3/7 + 14/8
= (3/5 + 2/5) + ( 4/7 + 3/7) + ( 2/8 + 14/8)
= 1 + 1 + 7/4
= 2 + 7/4 = 15/4
c , 8/7 + 7/6 + 5/8 + 10/12 + 24/28 + 6/16
= c , 8/7 + 7/6 + 5/8 + 5/6 + 6/7 + 1/2
= (8/7 + 6/7) + (7/6 + 5/6) + 5/8 + 1/2
= 14/7 + 12/6 + 5/8 + 1/2
= 2 + 2 + 5/8 + 1/2
= 4 + 9/8 = 41/8
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
Câu 1 : Trả lời : x =236
Câu 2 : Trả lời : x = 221
Câu 3 : Trả lời : x = 4815
Câu 4 : a, 5004 g
b, 30 kg
c, 600 kg
d, 11020 kg
Câu 1: Trả lời: x = 236
Câu 2: Trả lời: x = 221
Câu 3: Trả lời: x = 4815
Câu 4: Trả lời: a) 5004 kg b) 30 kg c) 600 kg d) 11020 kg
Chúc e học tốt và nhớ k cho c em nhé!
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
\(1.a)\frac{5}{3}-\frac{1}{4}+\frac{1}{3}-\frac{3}{4}\)
\(=\left(\frac{5}{3}+\frac{1}{3}\right)-\left(\frac{1}{4}+\frac{3}{4}\right)\)
\(=2-1\)
\(=1\)
\(b)\frac{2}{7}\times\frac{1}{5}+\frac{2}{7}\times\frac{4}{5}\)
\(=\frac{2}{7}\times\left(\frac{1}{5}+\frac{4}{5}\right)\)
\(=\frac{2}{7}\times1\)
\(=\frac{2}{7}\)
\(2.a)\frac{5}{6}+\frac{7}{12}-\frac{2}{9}\)
\(=\frac{30}{36}+\frac{21}{36}-\frac{8}{36}\)
\(=\frac{43}{36}\)
\(b)\frac{4}{9}\times\frac{5}{8}+\frac{1}{6}\)
\(=\frac{5}{18}+\frac{1}{6}=\frac{5}{18}+\frac{3}{18}\)
\(=\frac{8}{18}=\frac{4}{9}\)
\(c)2:\frac{3}{11}-\frac{13}{12}\)
\(=2\times\frac{11}{3}-\frac{13}{12}\)
\(=\frac{22}{3}-\frac{13}{12}\)
\(=\frac{25}{4}\)
a) 11/12 x 9/19 - 22/24 x 6/19 + 11/12 x 16/19.
= 11/12 x 9/19 - 11/12 x 6/19 + 11/12 x 16/19.
=11/12 x ( 9/19 -6/19 + 16/19)
=11/12x 1
=11/12
mình biết câu a/ thôi
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)
= 18 x 100 = 1800
A) 142 x 12 + 142 x 18
= 142 x ( 12 + 18 )
= 142 x 30
= 4260
B) 49 x 365 - 39 x 365 ;
= 365 x ( 49 - 39 )
= 365 x 10
= 3650
C) 4 x 18 x 25
= 4x 25 x 18
= 100 x 18
= 1800
\(a)75:x-57:x=6\)
⇔ \(\left(75-57\right):x=6\)
⇔ \(18:x=6\)
⇔ \(x\) \(=3\)
Vậy x = 3
\(b)18:x+12:x-6:x=4\)
⇔ \(\left(18+12-6\right):x=4\)
⇔ \(24:x=4\)
⇔ \(x=6\)
Vậy x = 6
a) 75 : x - 57 : x = 6
⇔ ( 75 - 57 ) : x = 6
⇔ 18 : x = 6
⇔ x = 18 : 6 = 3
Vậy x = 3.
b) 18 : x + 12 : x - 6 : x = 4
⇔ ( 18 + 12 - 6 ) : x = 4
⇔ 24 : x = 4
⇔ x = 24 : 4 = 6.
Vậy x = 6.