定义一种新运算a*b=a+b/a-b 计算-2*(-6*3)的值

定义一种新运算a*b=a+b/a-b 计算-2*(-6*3)的值
定义一种新运算a*b=a+b/a-b 计算-2*(-6*3)的值

定义一种新运算a*b=a+b/a-b 计算-2*(-6*3)的值
a*b=(a+b)/(a-b)
-6*3=(-6+3)/(-6-3)
=(-3)/(-9)
=1/3
-2*(-6*3)=-2*(1/3)
=(-2+1/3)/(-2-1/3)
=(-5/3)/(-7/3)
=5/7

-2*(-6*3)=-2*(-6+3/（-6)-3)=-2*(-19/2)=-2+(-19/2)/(-2)+19/2=65/4

因为：a*b=a+b/a-b
所以：-6*3=（-6+3)/(-6-3)=-1/3
所以可得：-2*(-6*3)=-2*（-1/3)=[-2+(-1/3)]/[(-2)-(-1/3)]=(-7/3)/(-5/3)=7/5

5/7.
-6*3=(-6+3)/(-6-3)=1/3
-2*(1/3)=(-2+1/3)/(-2-1/3)=5/7