Tim x biet
a)\(\frac{8}{23}.\frac{46}{24}-x=\frac{1}{3}\)
b) \(\frac{10}{12}:x=\frac{28}{9}.\frac{3}{56}\)
c) \(\frac{x-12}{4}=\frac{1}{2}\)
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a) \(\frac{x+1}{3}=\frac{x-2}{4}\)
=> (x+1).4 = (x - 2) . 3
=> 4x + 4 = 3x - 6
=> 4x - 3x = - 6 - 4
=> x = - 10
b) \(\frac{x-6}{7}+\frac{x-7}{8}+\frac{x-8}{9}=\frac{x-9}{10}+\frac{x-10}{11}+\frac{x-11}{12}\)
\(\Rightarrow\left(\frac{x-6}{7}+1\right)+\left(\frac{x-7}{8}+1\right)+\left(\frac{x-8}{9}+1\right)=\left(\frac{x-9}{10}+1\right)+\left(\frac{x-10}{11}+1\right)+\left(\frac{x-11}{12}+1\right)\)
\(\Rightarrow\frac{x+1}{7}+\frac{x+1}{8}+\frac{x+1}{9}=\frac{x+1}{10}+\frac{x+1}{11}+\frac{x+1}{12}\)
\(\Rightarrow\frac{x+1}{7}+\frac{x+1}{8}+\frac{x+1}{9}-\frac{x+1}{10}-\frac{x+1}{11}-\frac{x+1}{12}\) = 0
\(\Rightarrow\left(x+1\right).\left(\frac{1}{7}+\frac{1}{8}+\frac{1}{9}-\frac{1}{10}-\frac{1}{11}-\frac{1}{12}\right)\)
Vì \(\frac{1}{7}+\frac{1}{8}+\frac{1}{9}-\frac{1}{10}-\frac{1}{11}-\frac{1}{12}\ne0\) nên x + 1 =0
=> x = -1
c) Xem lại đề
#)Giải :
a) x + 2x + 3x + ... + 100x = - 213
=> 100x + ( 2 + 3 + 4 + ... + 100 ) = - 213
=> 100x + 5049 = - 213
<=> 100x = - 5262
<=> x = - 52,62
#)Giải :
b) \(\frac{1}{2}x-\frac{1}{3}=\frac{1}{4}x-\frac{1}{6}\)
\(\Rightarrow\frac{1}{2}x+\frac{1}{4}x=\frac{1}{3}+\frac{1}{6}\)
\(\Rightarrow\frac{1}{2}x+\frac{1}{4}x=\frac{1}{2}\)
\(\Rightarrow\left(\frac{1}{2}+\frac{1}{4}\right)x=\frac{1}{2}\)
\(\Rightarrow\frac{3}{4}x=\frac{1}{2}\)
\(\Leftrightarrow x=\frac{2}{3}\)
mk muốn xem bài của mk đúng hay sai thôi !
chứ làm thì mk làm xong rồi !
a, Câu hỏi của Nguyễn Ánh Ngân - Toán lớp 6 - Học toán với OnlineMath
b, Câu hỏi của Vũ Xuân Hiếu - Toán lớp 6 | Học trực tuyến
c)
Bài 1:
\(\frac{7}{12}+\frac{-8}{15}=\frac{7}{12}-\frac{8}{15}=\frac{35}{60}-\frac{32}{60}=\frac{3}{60}=\frac{1}{20}\)
\(\frac{5}{12}+\frac{-8}{15}=\frac{5}{12}-\frac{8}{15}=\frac{25}{60}-\frac{32}{60}=\frac{-7}{60}\)
Bài 2:
\(a,x-23=-56\)
\(x=-56+23\)
\(x=-33\)
\(b,2x-36=24\)
\(2x=60\)
\(x=30\)
\(c,x-\frac{4}{5}=\frac{3}{2}\)
\(x=\frac{3}{2}+\frac{4}{5}=\frac{23}{10}\)
\(d,x-46=123\)
\(x=123+46=169\)
\(e,2x-25=-45\)
\(2x=-20\)
\(x=-10\)
\(f,x-\frac{2}{3}=-\frac{7}{5}\)
\(x=-\frac{7}{5}+\frac{2}{3}=-\frac{11}{15}\)
=.= hk tốt!!
a) \(x-\frac{10}{3}=\frac{7}{15}\cdot\frac{3}{5}\) b) \(x+\frac{3}{22}=\frac{27}{121}\cdot\frac{11}{9}\)
\(\Leftrightarrow x-\frac{10}{3}=\frac{7}{25}\) \(\Leftrightarrow x+\frac{3}{22}=\frac{3}{11}\)
\(\Rightarrow x=\frac{7}{25}+\frac{10}{3}\) \(\Rightarrow x=\frac{3}{11}-\frac{3}{22}\)
\(x=\frac{271}{75}\) \(x=\frac{3}{22}\)
c) \(\frac{8}{23}.\frac{46}{24}-x=\frac{1}{3}\) d) \(1-x=\frac{49}{65}.\frac{5}{7}\)
\(\Leftrightarrow\frac{2}{3}-x=\frac{1}{3}\) \(\Leftrightarrow1-x=\frac{7}{13}\)
\(\Rightarrow x=\frac{2}{3}-\frac{1}{3}\) \(\Rightarrow x=1-\frac{7}{13}\)
\(x=\frac{1}{3}\) \(x=\frac{6}{13}\)
\(\frac{8}{23}\cdot\frac{46}{24}-x=\frac{1}{3}\)
=> \(\frac{2}{3}-x=\frac{1}{3}\)
=> \(x=\frac{1}{3}\)
\(\frac{10}{12}\div x=\frac{28}{9}\cdot\frac{3}{56}\)
=> \(\frac{10}{12}\div x=\frac{1}{6}\)
=> \(x=\frac{60}{12}=5\)
\(\frac{x-12}{4}=\frac{1}{2}\)
=> \(\left(x-12\right)\cdot2=4\cdot1\)
=> \(2x-24=4\)
=> \(2x=28\)
=> \(x=14\)