3x+1+x-1 / 2x^2
the +1 and -1 add up to 0, so they go away
3x + x / 2x^2
the x's on the top add up to 4x, so
4x / 2x^2
the x^2 on the bottom is sort of like x*x
4x / 2*x*x
x / x = 1, so an x from the top and an x from the bottom cancel out and go away, leaving
4 / 2*x
the 4 on the top is sort of like 2*2
2*2 / 2*x
2 / 2 = 1, so a 2 from the top and a 2 from the bottom cancel out and go away, leaving
2 / x
Answer: 2/x