求代数式的值已知x=1/3,y=1/4,求代数式x-(x+y)+(x+2y)+……(x+103y)的值

问题描述:

求代数式的值已知x=1/3,y=1/4,求代数式x-(x+y)+(x+2y)+……(x+103y)的值

x-(x+y)+(x+2y)+……(x+103y)
=-y+(x+2y)+(x+3y)+……(x+103y)
=(103-2+1)*x+(2+3+……+103-1)*y
=102*x+(105*51-1)*y
=34+1338.5
=1372.5