初一数学(化简.求值)(3x-5y)+(-3+y)其中x=5,y=3

问题描述:

初一数学(化简.求值)
(3x-5y)+(-3+y)其中x=5,y=3


(3x-5y)+(-3+y)
=3x-5y-3+y
=3x-4y-3
当x=5,y=3 时
原式=3×5-4×3-3
=0

(3x-5y)+(-3+y)
=3x-5y-3+y
=3x-4y-3
当x=5,y=3 时
3x-4y-3
=3×5-4×3-3
=0

(3x-5y)+(-3+y)
=3x-5y-3+y
=3x-4y-3
=3×5-4×3-3
=0

把x=5,y=3 代入式中:
(3x-5y)+(-3+y)=0+0=0