Question

初三数学题(高手请进)在线等!!!

已知b-a=1/7,2a^2+a=1/4,求b/a-a的值?(用简便方法)
要有详解过程,在线等!!!!

Answer 1

b/a-a=(b-a^2)/a

2a^2+a=1/4
a^2+a/2=1/8
a^2+a/2+1/16=3/16
(a+1/4)^2=3/16
a=（根3-1）/4或（-根3-1）/4

Answer 2

b-a=1/7 => b=a+1/7
2a^2+a=1/4 => a^2=1/8-a/2
b/a-a=(b-a^2)/a
=(a+1/71/8+a/2)/a
=3/2+a/56