Question

方程组｛2x-1/5+3y-2/4=2 3x+1/3-3y+2-4/3

Answer 1

2x-1/5+3y-2/4=2
8x-4+15y-10=40
8x+15y=54 (1)

3x+1/3-3y+2=4/3
3x+1-9y+6=4
x-3y=-1 (2)
(1)+(2)×5
8x+5x=54-5
x=49/13
y=(x+1)/3=62/39

Answer 2

f(-1/2)=0
x<0增函数
所以0>log1/4(x)>=-1/2
即(1/4)^0<x<=(1/4)^(-1/2)
1<x<=2

偶函数则f(1/2)=0
且x>0递减
所以0<log1/4(x)<=1/2
即(1/4)^0>x>=(1/4)^(1/2)
1/2<=x<1

综上
1/2<=x<1,1<x<=2