(13/3 - 18/5) :11/4 =?
Lưu ý: dấu "/" thay cho phân số
Giúp cho mình nha
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a) \(\frac{1}{2}=\frac{2}{4}=\frac{3}{6}=\frac{4}{8}=\frac{5}{10}=\frac{6}{12}\)b) \(\frac{25}{40}=\frac{5}{8}=\frac{10}{16}=\frac{15}{24}=\frac{20}{32}=\frac{30}{48}\)
c) \(\frac{18}{24}=\frac{3}{4}=\frac{6}{8}=\frac{9}{12}=\frac{12}{16}=\frac{15}{20}\)
a) \(\frac{1}{2}\) = \(\frac{2}{4}\) = \(\frac{3}{6}\) = \(\frac{4}{8}\) = \(\frac{5}{10}\) = \(\frac{6}{12}\)
b) \(\frac{25}{40}\) = \(\frac{5}{8}\) = \(\frac{10}{16}\) = \(\frac{15}{24}\) = \(\frac{20}{32}\) = \(\frac{30}{48}\)
c) \(\frac{18}{24}\) = \(\frac{3}{4}\) = \(\frac{6}{8}\) = \(\frac{9}{12}\) = \(\frac{12}{16}\) = \(\frac{15}{20}\)
Ta có \(\dfrac{2}{1\cdot5}+\dfrac{2}{5\cdot9}+\dfrac{2}{9\cdot13}+...+\dfrac{2}{x\left(x+4\right)}=\dfrac{56}{113}\)
\(\dfrac{1}{2}\left(\dfrac{4}{1\cdot5}+\dfrac{4}{5\cdot9}+\dfrac{4}{9\cdot13}+...+\dfrac{4}{x\left(x+4\right)}\right)=\dfrac{56}{113}\)
\(1-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{13}+...+\dfrac{1}{x}-\dfrac{1}{x+4}=\dfrac{56}{113}:\dfrac{1}{2}\)
\(1-\dfrac{1}{x+4}=\dfrac{112}{113}\)
\(\dfrac{1}{x+4}=1-\dfrac{112}{113}=\dfrac{1}{113}\)
x + 4 = 113 ⇒ x = 109
\(\dfrac{2}{1.5}+\dfrac{2}{5.9}+...+\dfrac{2}{x\left(x+4\right)}=\dfrac{56}{113}\)
Xét: \(A=\dfrac{2}{1.5}+\dfrac{2}{5.9}+...+\dfrac{2}{x\left(x+4\right)}\)
\(A=\dfrac{1}{2}.\left(1-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{9}+...+\dfrac{1}{x-4}-\dfrac{1}{x}+\dfrac{1}{x}-\dfrac{1}{x+4}\right)\)
\(A=\dfrac{1}{2}.\left(1-\dfrac{1}{x+4}\right)\)
Với \(A=\dfrac{56}{113}\) thì
\(\dfrac{1}{2}.\left(1-\dfrac{1}{x+4}\right)=\dfrac{56}{113}\)
\(\left(1-\dfrac{1}{x+4}\right)=\dfrac{112}{113}\)
\(\dfrac{1}{x+4}=\dfrac{1}{113}\)
\(x=109\)
5^2x -3 -2.25 = 25.3
5^2x -3 -50 = 75
5^2x - 53 = 75
=> 5^2x = 128
de co sai khong z ban mk nhom cung k ra
vậy mình trả lời nhé mới nghĩ ra
5^2x- 3-2.5^ 2 = 5^2. 3
5^2x- 3- 2.5^2= 25 .3
5^2x- 3-2.5^2 = 75
5^2x - 3- 50 =75
5^2x - 3= 75+ 50
5^2x - 3= 125
5^2x -3 = 5^3
2x- 3 = 3
2x = 3+ 3
x= 6 : 2
x= 3
[ 5 ^( 2x-3) bạn ạ ]
Vì *81* Chia hết cho 2 và 5 nên * hàng đơn vị = 0
Ta có:*810
Vì *810 : hết cho 3 và 9 nên * =0;9
Vậy:0810;9810
Nó ra như này, rồi click đây và nhập số vào, xong thì nhấp đồng ý
\(\frac{x}{5}-\frac{3}{7}=\frac{10}{13}\)
\(\Rightarrow\frac{91x}{455}-\frac{195}{455}=\frac{350}{455}\)
\(\Rightarrow91x-195=350\)
\(\Rightarrow91x=545\)
\(\Rightarrow x=\frac{545}{91}\)
\(\frac{-3x}{4}+\frac{1}{3}=\frac{11}{5}\)
\(\Rightarrow\frac{-45x}{60}+\frac{20}{60}=\frac{132}{60}\)
\(\Rightarrow-45x+20=132\)
\(\Rightarrow-45x=112\)
\(\Rightarrow x=-\frac{112}{45}\)
a, \(\dfrac{4}{7}\). \(\dfrac{a}{b}\) - \(\dfrac{1}{3}\) = \(\dfrac{1}{21}\)
\(\dfrac{4}{7}\).\(\dfrac{a}{b}\) = \(\dfrac{1}{21}\) + \(\dfrac{1}{3}\)
\(\dfrac{4}{7}\).\(\dfrac{a}{b}\) = \(\dfrac{8}{21}\)
\(\dfrac{a}{b}\) = \(\dfrac{8}{21}\):\(\dfrac{4}{7}\)
\(\dfrac{a}{b}\) = \(\dfrac{2}{3}\)
b, \(\dfrac{a}{b}\) + \(\dfrac{2}{3}\).\(\dfrac{1}{3}\) = \(\dfrac{2}{3}\)
\(\dfrac{a}{b}\) + \(\dfrac{2}{9}\) = \(\dfrac{2}{3}\)
\(\dfrac{a}{b}\) = \(\dfrac{2}{3}\) - \(\dfrac{2}{9}\)
\(\dfrac{a}{b}\) = \(\dfrac{4}{9}\)
c, \(\dfrac{a}{b}\) - \(\dfrac{1}{2}.\)\(\dfrac{2}{3}\) = \(\dfrac{2}{7}\)
\(\dfrac{a}{b}\) - \(\dfrac{1}{3}\) = \(\dfrac{2}{7}\)
\(\dfrac{a}{b}\) = \(\dfrac{2}{7}\) + \(\dfrac{1}{3}\)
\(\dfrac{a}{b}\) = \(\dfrac{13}{21}\)
d, \(\dfrac{11}{13}\): \(\dfrac{a}{b}\): \(\dfrac{2}{3}\) = 2\(\dfrac{7}{13}\)
\(\dfrac{11}{13}\): \(\dfrac{a}{b}\):\(\dfrac{2}{3}\) = \(\dfrac{33}{13}\)
\(\dfrac{11}{13}\): \(\dfrac{a}{b}\) = \(\dfrac{33}{13}\) \(\times\) \(\dfrac{2}{3}\)
\(\dfrac{11}{13}\): \(\dfrac{a}{b}\) = \(\dfrac{66}{39}\)
\(\dfrac{a}{b}\) = \(\dfrac{11}{13}\) : \(\dfrac{66}{39}\)
\(\dfrac{a}{b}\) = \(\dfrac{1}{2}\)
=44/165
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