bài 1 :
`a)``3(x-5)-10=2(x-2)`
`3x-15-10 =2x-4`
`3x-2x =-4+15+10`
`x =21`
`b)``(x-1)/2 -x+1 = (2x+1) /3`
`(x-1)/2- (2x)/2 +2/2 = (2x+1) /3`
`(x-1-2x-2) /2 = (2x+1) /3`
`(-x-3)/2 = (2x+1) /3`
`(-x-3)3 /6 = ((2x+1)2) /6`
` -3x-9 =4x+2`
`-3x-4x = 2+9`
` -7x = 11`
` x = -11/7`
c) `x(2x-5)+2(5-2x)=0`
`2x^2-5x+10-4x=0`
`2x^2-9x+10 =0`
`x=2`