当x-3y=0时,求(x二次方+xy+2y二次方)÷(x二次方-xy+y二次方)的值
问题描述:
当x-3y=0时,求(x二次方+xy+2y二次方)÷(x二次方-xy+y二次方)的值
答
∵x-3y=0
∴x=3y
∴(x²+xy+2y²)÷(x²-xy+y²)
=[(3y)²+(3y)y+2y²]÷[(3y)²-(3y)y+y²]
=(9y²+3y²+y²)÷(9y²-3y²+y²)
=13y²÷7y²
=13÷7
=7分之13
=1又7分之6