(1)计算：a-(a^2)/(a+1)-1 (2)计算：3x/(x-4y)+(x+y)/(4y-x)-7y/(x-4y)

题目

(1)计算：a-(a^2)/(a+1)-1 (2)计算：3x/(x-4y)+(x+y)/(4y-x)-7y/(x-4y)
(3)计算：x(2-1/x)+x/x^2-2x*(x^2-4)
(4)计算：(x-3)/(2x-4)÷(5/x-2--2)
(5)计算：m/m+3-6/9-m^2÷2/m-3
(6)计算：(3a/a-3-a/a+3)*a^2-9/a

答案

(1) a-(a²)/(a+1)-1
=(a²+a-a²-a-1)/(a+1)
=-1/(a+1)
(2) 3x/(x-4y)+(x+y)/(4y-x)-7y/(x-4y)
= (3x-x-y-7y)/(x-4y)
=(2x-8y)/(x-4y)
=2
(3) x(2-1/x)+x/x²-2x*(x²-4)
=2x-1+1/x-2x³+8x
=10x-2x³+1/x-1
(4) (x-3)/(2x-4)÷(5/x-2)
=(x-3)/(2x-4) *(x-2)/5
=(x-3)/10
(5) m/m+3-6/9-m²÷2/m-3
=m/(m+3)-6/[(m+3)(3-m)]*(m-3)/2
=m/(m+3)+3/(m+3)
=(m+3)/(m+3)
=1
(6) (3a/a-3-a/a+3)*a²-9/a
=[3a(a+3)-a(a-3)]/(a²-9) *(a²-9)/a
=[3a(a+3)-a(a-3)]/a
=3a+9-a+3
=2a+12