Interval Notation for Set Intersection and Union

AI Thread Summary
The discussion clarifies the intersections and unions of the given intervals A, B, and C. The correct intersections are A∩B = (3, 5) and A∩C = [0, 4], while the unions are A∪B = [-3, 8) and A∪C = A = [-3, 5). There is a possibility of typographical errors in the book's answers, as it incorrectly states A∩B and A∩C. Additionally, C is a subset of A, confirming that A∩C equals C. The confusion stems from mixing up intersection and union concepts, which are distinct operations in set theory.
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Homework Statement


Consider the following intervals:

A = [-3,5), B = (3,8), C = (0,4]

Find: A\capB and A\capC

The Attempt at a Solution



I thought that: A\capB=(3,5) and that A\capC=[0,4] as that is the intersection point, but this book (Schaum's Probability Outlines) says that A\capB=[-3,8) and A\capC=[-3,5)

I'm looking to confirm that the book might be wrong (Amazon reviews indicate a lot of typographical errors) and instead maybe their answer refers to A\cup B and A\cup C perhaps? Or am I getting confused?

Thanks!
 
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The book answers are for union \cup, and you are really close to correct with your answers for intersection \cap. It could be a typo in either question or answer.
 
Yes, A\cap B= (3, 5) while A\cup B= [-3, 8) as Joffan says. A\cup C= [-3, 5). But A\cap C is NOT [0, 4] because 0 is not in C.
In fact, C is a subset of A so A\cap C= C and A\cup C= A.
 
Since ##px^9+q## is the factor, then ##x^9=\frac{-q}{p}## will be one of the roots. Let ##f(x)=27x^{18}+bx^9+70##, then: $$27\left(\frac{-q}{p}\right)^2+b\left(\frac{-q}{p}\right)+70=0$$ $$b=27 \frac{q}{p}+70 \frac{p}{q}$$ $$b=\frac{27q^2+70p^2}{pq}$$ From this expression, it looks like there is no greatest value of ##b## because increasing the value of ##p## and ##q## will also increase the value of ##b##. How to find the greatest value of ##b##? Thanks

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