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A) 9 - 13/4 + 4/3 : 2
=9 - 13/4 + 2/3
=9 - 47/12
=61/12
B) 13/14 : X + 4/5 = 9
13/4 :X = 9 - 4/5
13/4 : X = 41/5
X=13/4 : 41/5
X=65/164
Bai 1.
a) 9 - 13/4 +4/3 : 2
= 9 - 13/4 +4/3 x 1/2
= 9 - 13/4 + 2/3
= 36/4 - 13/4 + 2/3
= 23/4 + 2/3
= 69/12 + 8/12
= 77/12
Bai 2. Tim x
13/4 : x + 4/5 = 9
13/4 : x = 9 - 4/5
13/4 : x = 45/5 - 4/5
13/4 : x = 41/5
x = 13/4 : 41/5
x = 13/4 x 5/41
x = 65/164
Vay x = 65/164
có ai giúc mk ko mk đăng nhiều lần rồi răng ko ai chịu giúc nhỉ
\(\frac{1}{5.8}\)\(+\frac{1}{8.11}+\frac{1}{11.14}+...+\frac{1}{x\left(x+3\right)}=\frac{98}{1545}\)
\(\Leftrightarrow\frac{3}{5.8}+\frac{3}{8.11}+\frac{3}{11.14}+...+\frac{3}{x\left(x+3\right)}=3.\frac{98}{1545}\)
\(\Leftrightarrow\frac{3}{5.8}+\frac{3}{8.11}+\frac{3}{11.14}+...+\frac{3}{x\left(x+3\right)}=\frac{98}{515}\)
\(\Leftrightarrow\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}+...+\frac{1}{x}-\frac{1}{x+3}=\frac{98}{515}\)
\(\Leftrightarrow\frac{1}{5}-\frac{1}{x+3}=\frac{98}{515}\)
\(\Leftrightarrow\frac{1}{x+3}=\frac{1}{5}-\frac{98}{515}\)
\(\Leftrightarrow\frac{1}{x+3}=\frac{1}{103}\)
\(\Leftrightarrow x+3=103\)
\(\Leftrightarrow x\)\(=103-3\)
\(\Leftrightarrow x\)\(=100\)
Vậy x = 100
~~~~~~~Hok tốt~~~~~~~~
ta có \(\frac{1}{5.8}+\frac{1}{8.11}+...\frac{1}{x.\left(x+3\right)}\)\(=\frac{1}{3}\left(\frac{3}{5.8}+\frac{3}{8.11}+...+\frac{3}{x.\left(x+3\right)}\right)\)\(=\frac{1}{3}.\left(\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+...+\frac{1}{x}-\frac{1}{x+3}\right)\)
\(\Rightarrow\frac{1}{3}.\left(\frac{1}{5}-\frac{1}{x+3}\right)=\frac{98}{1545}\)
\(\Rightarrow\frac{1}{5}-\frac{1}{x+3}=\frac{98}{1545}:\frac{1}{3}=\frac{98}{515}\)
\(\Rightarrow\frac{1}{x+3}=\frac{1}{5}-\frac{98}{515}=\frac{1}{103}\)
\(\Rightarrow x+3=103\)
\(\Rightarrow x=100\)
nhớ k nha
Xin lỗi bạn nhé mình chỉ làm được bài 2 thôi!
Bài 2:
a) y + y x 1/3 : 2/9 + y : 2/7 = 252
y x 1 + y x 1/3 x 9/2 + y x 7/2 = 252
y x 1 + y x 3/2 + y x 7/2 = 252
y x ( 1 + 3/2 + 7/2) = 252
y x 6 = 252
y = 252 : 6
y =42
b) ( 324 : 3 + 12 - y) : 7 = 3
( 108 + 12 - y) = 3 x 7
120 - y = 21
y = 120 - 21
y 99
1.
a ) x * 3.1 + x * 1,4 = 2,7
x * ( 3,1 + 1,4 ) = 27
x * 4,5 = 27
x = 27 : 4,5=6
Vậy x=6
b) x : 3,08 -17,8 = 158 , 2
x : 3, 08 = 158,2 + 17,8
x : 3, 08 = 176
x = 176 * 3,08
x = 542,08
Vậy x= 542,08
\(1\frac{2}{5}\)tấn = 1400 kg
1) \(x\times3,1+x\times1,4=27\)
=> \(x\times\left(3,1+1,4\right)=27\)
=> \(x\times4,5=27\)
=> \(x=27:4,5\)
=> \(x=6\)