,已知y1=5x+2,y2=4-3x 当x取何值时y1=y2?当X取何值时y1比y2大5?

问题描述:

,已知y1=5x+2,y2=4-3x 当x取何值时y1=y2?当X取何值时y1比y2大5?

1、当y1=y2时:5x+2=4-3x 得出x=1/4
2、当y1比y2大5:5x+2-(4-3x )=5 得出x=7/8

y1=y2 则5x+2=4-3x x=0.25
y1比y2大5 则y1-y2>5 5x+2-(4-3x )>5, x>7/8

tt葩葩tt :
当y1=y2时,
即5x+2=4-3x
5x+3x=4-2
8x=2
x=1/4
当y1比y2大5时,
即5x+2=4-3x+5
5x+3x=9-2
8x=7
x=7/8

(1)5x+2=4-3x x=1/4
(2)5x+2=4-3x +5 x=7/8