#)Giải :
\(123-5\left(x+4\right)=38\)
\(\Leftrightarrow5\left(x+4\right)=85\)
\(\Leftrightarrow x+4=17\)
\(\Leftrightarrow x=13\)
\(\left(3x-16\right)343=2.2401\)
\(\Leftrightarrow\left(3x-16\right)343=4802\)
\(\Leftrightarrow3x-16=14\)
\(\Leftrightarrow3x=30\)
\(\Leftrightarrow x=10\)
\(\left(2600+6400\right)-3x=1200\)
\(\Leftrightarrow9000-3x=1200\)
\(\Leftrightarrow3x=7800\)
\(\Leftrightarrow x=2600\)
P/s : Câu cuối cùng lỗi chỗ b4 ph k ? hay là tìm cả b và x thế ???
\(123-5\left(x+4\right)=38\)
\(=>123-5x-20=38\)
\(=>-5x=-123+20+38\)
\(=>-5x=-65\)
\(=>x=13\)
b, \(\left(3x-16\right)343=2.2401\)
=>1029x -5488= 4802
=> 1029x=5488+4802
=> 1029x= 10290
=> x=10
c, (2600+6400)-3x=1200
=> 9000-3x=1200
=> -3x= -9000+1200
=> -3x= -7800
=> x=2600
d,
k hiểu đề
6x-72:2-84.28=5628
=> 6x-36-2352= 5628
=> 6x= 36+2352+5628
=> 6x= 8016
=> x= 1336