Y=X^2+1/2-3x X为何值时,Y为正数?Y为负数
问题描述：
Y=X^2+1/2-3x X为何值时,Y为正数?Y为负数
答
Y=X^2+1/2-3x
y为正数时,Y>0
x^2-3x+1/2>0
x^2-3x+9/4>9/4-1/2
(x-3/2)^2>7/4
x-3/2>根号7 /2或x-3/2即x>3/2+根号7/2或xY是负数时:
x^2-3x+1/2同上,解得:3/2-根号7/2
答
Y=X^2+1/2-3x
y为正数时,Y>0
x^2-3x+1/2>0
x^2-3x+9/4>9/4-1/2
(x-3/2)^2>7/4
x-3/2>根号7 /2或x-3/2