C and D are sets of real numbers defined as follows

Question

C ={ w | w > 2 }

 

D = { w | w ≥ 7 }

 

Write C ∪ D and C n D using interval notation.
If the set is empty, write ∅

Answer 1

Get two colors, BLUE AND YELLOW

 

Draw the number line.

 

At 2 draw a small open circle. Shade the number line from 2 going to your right, going through 2,3,4,5,67,8,9,....... in BLUE

 

At 7 draw a small closed circle in YELLOW, and share from 7 going to your right going through 7,8,9,10,11 in YELLOW

 

The green part is the intersection.

 

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Intersection means the elements they have in common.

Union means all of the elements together, but no duplicates.

 

SO C u  D = C

 

and C  intersect D = D