已知x=2013,y=2014,則(x+y)(x^2+y^2)/x^4-y^4=?
x^4-y^4=(x^2+y^2)(x+y)(x-y);
所以分式的值為-1.
已知x=2013,y=2014,求(x+y)(x^2+y^2)/x^4-y^4
由(x+y)(x^2+y^2)/x^4-y^4
=(x+y)(x^2+y^2)/(x^2+y^2)*(x^2-y^2)
=(x+y)/(x^2-y^2)
=(x+y)/(x-y)(x+y)
=1/(x-y)
=1/(2013-2014)
=-1
若xy滿足丨x+1丨+丨y-2013丨小於等於0,求xy的值
∵丨x+1丨>=0,|y-2013|>=0
∴x+1=0,y-2013=0
x=-1 y=2013
∴xy=-2013