4x-2y=-1 ①
x+4y=2 ②
①×2,得
8x-4y=-2 ③
②+③,得
9x=0
x=0
y=1/2
x/2<2(x-1)
两边乘2,得
x<4x-4
x<4/3
x/3>(x+2)/5
两边乘15,得
5x>3(x+2)
5x>3x+6
x>3
综上所述x<4/3或x>3
1/3(2-x)<3x-1
两边乘3,得
2-x<9x-3
-10x<-5
x>1/2
最小整数解是1
x^2+8x-15=0
x^2+8x=15
(x+2)(x-2)-4x(x-1)+(2x+1)^2
=x^2-4-4x^2+4x+4x^2+4x+1
=x^2+8x-3
=15-3
=12