a: =>-3(4x+1)=2(4x-1)-6x-8
=>-12x-3=8x-2-6x-8
=>-12x-3=2x-10
=>-14x=-7
=>x=1/2(nhận)
b: =>\(\dfrac{2x+19}{5\left(x-1\right)\left(x+1\right)}-\dfrac{17}{\left(x-1\right)\left(x+1\right)}=-\dfrac{3}{x-1}\)
=>\(2x+19-85=-15\left(x+1\right)\)
=>-15x-15=2x-66
=>-17x=-51
=>x=3(nhận)
c: =>3(5x-3)-2(5x-1)=-4
=>15x-9-10x+2=-4
=>5x-7=-4
=>5x=3
=>x=3/5(loại)