`a) => 4/5+x=4/45-3/7=-107/315`
`=> x=-107/315-4/5`
`=> x=-359/315`
`b) => 7x-1=0` hoặc `3x-1/2=0`
`=> 7x=1` hoặc `3x=1/2`
`=> x=1/7` hoặc `x=1/6`
`c)=> |3x-2|=1/3+14=43/3`
`=> 3x-2=43/3` hoặc `3x-2=-43/3`
`=> 3x=49/3` hoặc `3x=-37/3`
`=> x=49/9` hoặc `x=-37/9`
`d) => 5^(-2). (5^3)^x=5^x`
`=> 5^(-2). 5^(3x)=5^x`
`=> 5^(-2+3x)=5^x`
`=> -2+3x=x`
`=> 3x-x=2`
`=> 2x=2`
`=> x=1`