当x______时,分式1−x+5
当x______时,分式xx−1
当x______时,分式2x+4x+1
当x______时,3x−1
当x______时,(1−x)
当x______时,二次根式x+1
当x______时,x+3
(2011•昆明)当x______时,二次根式x−5
当x______时,二次根式x+3
当x______时,式子x+3
(1)当x_____时,分式2x+1分之2x-3有意义,当x______时,分式2x+1分之2x-3的值为0
当自变量x______时,函数y=5x+4的值大于0;当x______时,函数y=5x+4的值小于0.
当自变量x______时,函数y=5x+4的值大于0;当x______时,函数y=5x+4的值小于0.