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NastyAccident
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Homework Statement
Suppose f is a function with sets A and B.
1. Show that:
[tex]I_{f} \left(A \cap B\right) = I_{f} \left(A\right) \cap I_{f} \left(B\right)[/tex]
Inverse Image of F (A intersects B) = Inverse Image of F (A) intersects Inverse Image of B.
2. Show by giving a counter example that:
[tex]f\left(A \cap B\right) \neq f\left(A\right) \cap f \left(B\right)[/tex]
F (A intersects B) does not equal F (A) intersects F(B)
Homework Equations
Knowledge of Sets and Inverse Images
The Attempt at a Solution
1.
Let c be an element of [tex]I_{f} \left(A \cap B\right)[/tex].
By the definition of [tex]I_{f} \left(A \cap B\right) [/tex], there is a [tex]d\in(A \cap B)[/tex] so that [tex]I_{f}(d)=c[/tex].
Since, [tex]d\in(A \cap B)[/tex], [tex] d \in A & d \in B[/tex]. Since [tex]d\inA, I_{f}(d)\in I_{f}(A)[/tex]. This follows alongside [tex]d\inB, I_{f}(d)\inI_{f}(B)[/tex].
Since [tex]I_{f}(d)=c \in I_{f}(A) [/tex] and [tex]I_{f}(d)=c \in I_{f}(B), c = I_{f}(A)\capI_{f}(B)[/tex].
Thoughts? Also would I need to show that the [tex]I_{f}(A)\capI_{f}(B) \in I_{f} \left(A \cap B\right)[/tex] to show true equality?
2.
[tex]f\left(A \cap B\right) \neq f\left(A\right) \cap f \left(B\right)[/tex]
I'm thinking either the absolute value function or a square function of some sort would show that it is not equal. Though, I'm not sure how to proceed with depicting the counter example.
NA
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