計算:(1)(ab-b^2)÷a^2+b^2分のa^2-b^2·b/1(2)x^2+3x+2分のx+1+x^2+7x+12分のx+3

計算:(1)(ab-b^2)÷a^2+b^2分のa^2-b^2·b/1(2)x^2+3x+2分のx+1+x^2+7x+12分のx+3

1)(ab-b^2)÷[(a^2-b^2)/(a^2+b^2)]*(1/b)
=b(a-b)*[(a^2+b^2)/(a+b)(a-b)]*1/b
=(a^2+b^2)/(a+b)
2)x^2+3x+2のx+1+x^2+7x+12のx+3
=(x+1)/[(x+1)(x+2)]+(x+3)/[(x+3)(x+4)]
=1/(x+2)+1/(x+4)
=[(x+4)+(x+2)]/[(x+2)(x+4)]
=(2x+6)/(x+2)(x+4)