Question

初二数学题：分式计算

Answer 1

12/(m²-9)-2/(3-m)
=12/(m-3)(m+3)+2(m+3)/(m+3)(m-3)
=(12+2m+6)/(m-3)(M+3)
=2(m+9)/(m-3)(m+3)

[(x²-4)/(x²-4x+4)-(x-2)/(x+2)]÷x/(x-2)
=[(x²-4)(x+2)/(x-2)²(x+2)-(x-2)³/(x-2)²(x+2)]÷x/(x-2)
=[(x³-4x+2x²-8-x³+6x²-12x+8)/(x-2)²(x+2)]÷x/(x-2)
=(8x²-16x)/(x-2)²(x+2)÷x/(x-2)
=2x(x-2)/(x-2)²(x+2)÷x/(x-2)
=2/(x+2)

1/(y-x)+1/(2x-2y)
=2/2(y-x)-1/2(y-x)
=(2-1)/2(y-x)
=1/2(y-x)

Answer 2

12/m²-9 -2/3-m
=12/m²-9 -2(3+m)/(3-m)(3+m)
=12/m²-9 -6+2m/9-m²
=12/m²-9 +6+2m/m²-9
=2(m+9)/(m-3)(m+3)

Answer 3

1) 2M+18/(M^2-9)
2) 8/(X+2)
3) 1/(2(Y-X))

Answer 4

1.原式=12/[m+3][m-3]+2/[m+3][m-3]
=10/[m+3][m-3]
2.题目不清晰
3.原式=1/[y-x]-1/2[y-x]=2/2[y-x]-1/2[y-x]=1/2[y-x]