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x + 37,5 + x * 2 = 11.9
1/3 + x/3 * 1/6 = 7/18
4/7 : x * 3/2 + 1/7 = 13/7
Câu hỏi tương tự Đọc thêmToán lớp 5Lời giải:
$=\frac{16}{21}+\frac{2}{9}-\frac{2}{21}+\frac{3}{9}$
$=(\frac{16}{21}-\frac{2}{21})+(\frac{2}{9}+\frac{3}{9})$
$=\frac{14}{21}+\frac{5}{9}=\frac{2}{3}+\frac{5}{9}=\frac{11}{9}$
bài2 \(x\times\dfrac{15}{16}-x\times\dfrac{4}{16}=2\)
\(x\times\dfrac{11}{16}=2\)
\(x=2:\dfrac{11}{16}\)
\(x=\dfrac{32}{11}\)
Bài 1 :
\(\dfrac{x}{16}\times\left(2017-1\right)=2\)
\(\dfrac{x}{16}\times2016=2\)
\(\dfrac{x}{16}=\dfrac{2}{2016}\)
\(x=\dfrac{2}{2016}\times16\)
\(x=\dfrac{1}{63}\)
c] 7 * x + 8 * x + 9 * x + .... + 100 * x = 1025
(7+8+9+...+100)*x=1025
Coi A= 7+8+...+100
Số các số hạng của A là:
(100-7):1+1=94 (số)
=>A=(100+7)*94:2=5029
Ta lại có:
5029*x=1025
=>x=1025:5019=1025/5019
a, \(x.\left(\frac{3}{2}+\frac{1}{4}-\frac{1}{2}\right)=x.\left(\frac{6}{4}+\frac{1}{4}-\frac{2}{4}\right)=\frac{10}{9}\)
\(x.\frac{5}{4}=\frac{10}{9}\)
\(x=\frac{10}{9}:\frac{5}{4}=\frac{10}{9}.\frac{4}{5}=\frac{8}{9}\)
\(\frac{3}{2}.x-\frac{2}{7}.\left(x-\frac{7}{2}\right)=18\)
\(< =>\frac{3x}{2}-\frac{2x}{7}+1=18\)
\(< =>\frac{21x}{14}-\frac{4x}{14}=18-1\)
\(< =>\frac{x\left(21-4\right)}{14}=17< =>17x=17.14\)
\(< =>x=\frac{17.14}{17}=14\)
\(\dfrac{6}{7}\cdot\dfrac{8}{9}+\dfrac{7}{9}\cdot\dfrac{2}{7}-\dfrac{18}{21}\cdot\dfrac{1}{9}+\dfrac{7}{9}\cdot\dfrac{3}{7}\)
\(=\dfrac{6}{7}\cdot\dfrac{8}{9}-\dfrac{6}{7}\cdot\dfrac{1}{9}+\dfrac{7}{9}\left(\dfrac{2}{7}+\dfrac{3}{7}\right)\)
\(=\dfrac{6}{7}\left(\dfrac{8}{9}-\dfrac{1}{9}\right)+\dfrac{7}{9}\cdot\dfrac{5}{7}\)
\(=\dfrac{7}{9}\left(\dfrac{6}{7}+\dfrac{5}{7}\right)=\dfrac{7}{9}\cdot\dfrac{11}{7}=\dfrac{11}{9}\)
c] 7 * x + 8 * x + 9 * x + .....+ 100 * x = 1025
=> x (7 + 8 + 9 +...+ 100) = 1025
=> x * 5029 = 1025
=> x = 1025/5029
Mình chỉ làm 1 câu thôi nhé
a,
Ta có:
\(\frac{1}{7}+\frac{2}{7x}=\frac{3}{2}\)
\(\Rightarrow\frac{x+2}{7x}=\frac{3}{2}\)
=> 2x+4=21x
=> 4=19x
=> x=4/19
Chắc vậy á :)
\(\frac{1}{7}+\frac{2}{7}:x=\frac{3}{2}\)
\(\Rightarrow\frac{2}{7}:x=\frac{3}{2}-\frac{1}{7}\)
\(\Rightarrow\frac{2}{7}:x=\frac{21}{14}-\frac{2}{14}\)
\(\Rightarrow\frac{2}{7}:x=\frac{19}{14}\)
\(\Rightarrow x=\frac{2}{7}:\frac{19}{14}\)
\(\Rightarrow x=\frac{2}{7}\times\frac{14}{19}\)
\(\Rightarrow x=\frac{4}{19}\)
Vậy \(x=\frac{4}{19}\)
~ Ủng hộ nhé
\(\left(8\times18-5\times18-3\times18\right)\times x+2\times x=8\times7+24\)
\(18\times\left(8-5-3\right)\times x+2\times x=8\times7+24\)
\(0\times x+2\times x=8\times7+24\)
\(\left(0+2\right)\times x=8\times7+24\)
\(2\times x=8\times7+24\)
\(2\times x=56+24\)
\(2\times x=80\)
\(x=80:2\)
\(x=40\)
\(\dfrac{3}{2}.x-\dfrac{2}{7}.x< x-\dfrac{7}{2}\ge18\)
\(\Rightarrow\left\{{}\begin{matrix}x-\dfrac{7}{2}>\dfrac{3}{2}.x-\dfrac{2}{7}.x\\x-\dfrac{7}{2}\ge18\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}x-\dfrac{3}{2}.x+\dfrac{2}{7}.x>\dfrac{7}{2}\\x\ge18+\dfrac{7}{2}\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}\left(1-\dfrac{3}{2}+\dfrac{2}{7}\right).x>\dfrac{7}{2}\\x\ge\dfrac{36}{2}+\dfrac{7}{2}\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}\left(\dfrac{14}{14}-\dfrac{21}{14}+\dfrac{4}{14}\right).x>\dfrac{7}{2}\\x\ge\dfrac{43}{2}\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}\left(-\dfrac{3}{14}\right).x>\dfrac{7}{2}\\x\ge\dfrac{43}{2}\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}x< \dfrac{7}{2}:\left(-\dfrac{3}{14}\right)\\x\ge\dfrac{43}{2}\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}x< \dfrac{7}{2}.\left(-\dfrac{14}{3}\right)\\x\ge\dfrac{43}{2}\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}x< -\dfrac{49}{3}\\x\ge\dfrac{43}{2}\end{matrix}\right.\) \(\Rightarrow x\in\varnothing\)
Bài toán này kiến thức vượt lớp 5 (dấu . là dấu nhân)
giiups tui nhanh nhanh