There is only one element in q 1:A, so find the value of m.

There are two elements in q 2:A, and find the value of m.

Question 3: A is an empty set. Find the value of m.

1△= 0 4(m- 1)^2-4m^2=4m^2-8m+4-4m^2=4-8m=0 m = 1/2

2△& gt； 0 4(m- 1)^2-4m^2=4m^2-8m+4-4m^2=4-8m>； 0m & lt； 1/2

3△& lt； 0 4(m- 1)^2-4m^2=4m^2-8m+4-4m^2=4-8m<； 0m & gt； 1/2

Given the set a = {x | ax2+2x+ 1 = 0}, if there is at least one element in a, find the value range of a.

A = 0ax2+2x+1= 02x+1= 0x =-1/2a has only one element.

A is not equal to 0 △ > = 0 4-4a & gt； = 0 4a & lt= 4a & lt； = 1

A<= 1 A has at least one element.