好急><5題f.2 maths><.....(20點)

1. 8m-2mn/n^2-4n
=2m(4-n)/ n(n-4)
=2m(4-n)/ -n(4-n)
=-2m/n
2. 6p+4q-10/3p^2+2pq-5p
=2(3p+2q-5)/ p(3p+2q-5)
=2/p

simplify the following expressions.
3.x^3/5x+5y 除 x^4/ky+kx
=x^3/ 5(x+y) over x^4/k(x+y)
=x^3/5(x+y) * k(x+y)/x^4
=k/ 5x

4.2x/3(2x-y) - 5y/y-2x
= 2x / 3(2x-y) +5y/(2x-y)
=2x/3(2x-y) + 15y/3(2x-y)
=(2x+15y)/3(2x-y)

5.x-1/x+1 - x-3/x+3
=(x-1)/(x+1) - (x-3)/(x+3)
=(x-1)(x+3)/(x+1)(x+3) - (x-3)(x+1)/ (x+3)(x+1)
=(x^2+2x-3) / (x+1)(x+3) - (x^2-2x-3) / (x+3)(x+1)
=4x/ (x+1)(x+3)

You should use bracket properly.
e.g. (8m-2mn)/(n^2-4n)