Maths Algebraic Fractions 20點!

1)2 / ((m+n)(2m+n)) + 5 / ((m+n)(m-3n))= ( 2(m-3n) + 5(2m+n) ) / ( (m+n)(2m+n)(m-3n) )= (12m - n) / ( (m+n)(2m+n)(m-3n) )
2)4/(x²-2xy) + 6/(xy-2y²)= 4 / ( x(x - 2y) ) + 6 / ( y(x - 2y) )= (4y + 6x) / ( xy(x - 2y) ) = 2(2y + 3x) / ( xy(x - 2y) )
3)x / ((x-3)(2x+1)) - x / ((3-x)(3x-2))= ( x(3x-2) + x(2x+1) ) / ( (x-3)(2x+1)(3x-2)) ) = (5x² - x) / ( (x-3)(2x+1)(3x-2) ) = x(5x - 1) / ( (x-3)(2x+1)(3x-2) )
4)(3x² + x - 2) / (x² - 1)= (3x - 2) (x + 1) / ( (x - 1) (x + 1) )= (3x - 2) / (x - 1)
5)(x-4)(x+2) / (16 -x²) ÷ ( (x²+2x) / (x²+4x) )= (x-4)(x+2) / ( (4 -x)(4+x) ) * (x²+4x) / (x²+2x)= - (x+2) / (x+4) * x(x+4) / (x(x+2))= - 1

you ahould do it by yourself!!

2012-02-05 17:04:10 補充：
you should do it by yourself!

1. 2/(m+n)(2m+n) + 5/(m+n)(m-3n)
=(2(m-3n))/((m+n)(2m+n)(m-3n))+(5(2m+n))/((m+n)(m-3n)(2m+n))
=(2m-6n)/((m+n)(2m+n)(m-3n))+(10m+5n)/((m+n)(m-3n)(2m+n))
(3x-2)/(x-1)
5.(x-4)(x+2)/(16-x^2 )÷(x^2+2x)/(x^2+4x)
=((x-4)(x+2))/(16-x^2 )×(x^2+4x)/(x^2+2x)
=((x-4)(x+2))/(4^2-x^2 )×(x(x+4))/(x(x+2))
=((x-4)(x+2))/((4+x)(4-x))×(x(x+4))/(x(x+2))
=(x-4)/(4-x)
我不能肯定第5題的答案是正確的，敬請見諒。