rule
δ=(a- 1)^2-4a^2<; 0
Solution: a
or
a & gt 1/3
The function y = (2a 2-a) x is increasing function.
rule
2a^2-a>; 1
Solution: a
or
a & gt 1
A. At least one true proposition of B is to find the union of these two solution sets.
or
a & gt 1/3
A.b has one and only one true proposition.
- 1≤a & lt; - 1/2
Or 1/3
For reference only:
First of all, we won't discuss it. Find out the range where A satisfies A and B before discussing.
For a:
The solution set of x 2+(A- 1) x+A 2 ≤ 0 is an empty set.
Explain that the discriminant on the left is less than 0.
So this time: (a- 1) 2-4 * a 2
After simplification, we get:
3a^2+2a- 1>; 0
(a+ 1)(3a- 1)>0
So: a> 1/3
or
a & lt- 1.
For b:
The function y = (2a 2-a) x is increasing function.
This function is exponential, so when 2a 2-a >1,it is increasing function.
2a^2-a〉 1
2a^2-a- 1〉0
(a- 1)*(2a+ 1)>0
So: a> 1
or
a & lt- 1/2.
Now let's discuss that (1) A.B. has at least one true proposition.
It means that one or both of A and B can be established. By plotting on the number axis,
Easy to obtain:
a & lt- 1/2
Or a> 1/3.
Discussion (2) A.B. has one and only one true proposition.
It means that when A is established, B is not; Or b is true and a is not.
Look at it first: A holds, but B does not.
Draw through several axes: when drawing, A draws according to the above interval, and because B is not established, it draws its complementary set range.
If it intersects with A, it is easy to get: 1/3.
Similarly, when B holds, A does not.
Draw through several axes: when drawing, B draws according to the above interval, because A is not established, so draw its complement range.
When it intersects with B, it is easy to get:-1