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\(\frac{x}{13}\times\frac{15}{26}=\frac{5}{14}\)
\(\frac{x}{13}=\frac{5}{14}\times\frac{26}{15}=\frac{13}{21}\)
\(\Rightarrow21\times x=13\times13\)
\(\Rightarrow x=169:21=\frac{169}{21}\)
Vậy, .....
\(\frac{x}{13}.\frac{15}{26}=\frac{5}{14}\)
\(\Rightarrow\frac{x}{13}=\frac{5}{14}:\frac{15}{26}\)
\(\Rightarrow\frac{x}{13}=\frac{5}{14}.\frac{26}{15}\)
\(\Rightarrow\frac{x}{13}=\frac{13}{21}\)
\(\Rightarrow x=\frac{13}{21}.13\)
\(\Rightarrow x=\frac{169}{21}\)
Vậy \(x=\frac{169}{21}\)
\(\frac{x+16}{2000}+1+\frac{x+15}{2001}+1=\frac{x+14}{2002}+1+\frac{x+13}{2003}+1\)
\(\frac{x+2016}{2000}+\frac{x+2016}{2001}=\frac{x+2016}{2002}+\frac{x+2016}{2003}\)
\(\frac{x+2016}{2000}+\frac{x+2016}{2001}-\frac{x+2016}{2002}-\frac{x+2016}{2003}=0\)
\(\left(x+2016\right)\left(\frac{1}{2000}+\frac{1}{2001}-\frac{1}{2002}-\frac{1}{2003}\right)=0\)
\(x-2016=0\)
\(x=2016\)
b.\(\frac{1374.57+1374.34}{26.13+74.13+74}=\frac{1374.91}{1374}=91\)
a, 1990 . 1990 - 1982 . 1998
= ( 1982 + 8 ) . 1990 - 1982 . ( 1990 + 8 )
= 1982 .1990 + 8 .1990 - ( 1982 . 1990 + 8 . 1982 )
= 1982 . 1990 + 8 .1990 - 1982 . 1990 - 8 . 1982
= ( 1982 .1990 - 1982 . 1990 ) + ( 8 . 1990 - 8 . 1982 )
= 8 . ( 1990 - 1982 )
= 8 . 8
= 64
Mình sửa đề bài chút xíu nha 1992 thành 1982
a, 4,5 - 2x . 147 = 1114
2x . 147 = 4,5 - 1114
2x . 147 = -1109,5
2x = -1109,5 / 147
2x = \(-\dfrac{317}{42}\)
x = \(-\dfrac{317}{42}:2\)
x = \(-\dfrac{317}{84}\)
b, ( x + 14 - 13 ) : ( 2 + 16 - 14 ) = 746
( x + 1 ) : 4 = 746
x + 1 = 746 . 4
x + 1 = 2984
x = 2984 - 1
x = 2983
c, \(\dfrac{13}{15}-\left(\dfrac{13}{21}+x\right).\dfrac{7}{12}=\dfrac{7}{10}\)
\(\left(\dfrac{13}{21}+x\right).\dfrac{7}{12}=\dfrac{13}{15}-\dfrac{7}{10}\)
\(\left(\dfrac{13}{21}+x\right).\dfrac{7}{12}=\dfrac{1}{6}\)
\(\dfrac{13}{21}+x=\dfrac{1}{6}:\dfrac{7}{12}\)
\(\dfrac{13}{21}+x=\dfrac{2}{7}\)
\(x=\dfrac{2}{7}-\dfrac{13}{21}\)
\(x=-\dfrac{1}{3}\)
a) x - 13+x = -24-7 + x
2x-13 = -31 +x
2x-x = -31+13
x = -18
b) 12.20 = 15x
240 = 15x
x = 16
c) 42(-5) = 14x
-210 = 14x
x = -15
\(\dfrac{x-1}{10}+\dfrac{x-2}{11}+\dfrac{x-3}{12}=\dfrac{x-4}{13}+\dfrac{x-5}{14}+\dfrac{x-6}{15}\)
Dựa vào t/c dãy tỉ số = nhau ta có:
\(\dfrac{x-1+x-2+x-3}{10+11+12}=\dfrac{x-4+x-5+x-6}{13+14+15}\)
\(\dfrac{3x-6}{33}=\dfrac{3x-15}{42}\)
\(42\left(3x-6\right)=33\left(3x-15\right)\)
\(126x-252=99x-495\)
\(126-99x=594-252\)
\(27x=342\)
\(x=\dfrac{38}{3}\)