Question

IfA= {3, 6, 9, 12, 15, 18, 21),
B = {4, 8, 12, 16, 20},
C = {2, 4, 6, 8, 10, 12, 14, 16) and D= {5, 10, 15, 20), find A-B​

Answer 1

Answer:

A-B=3,6,9,15,18,21

I hope it's help you

Answer 2

✓ Given :

» A = { 3 , 6 , 9 , 12 , 15 , 18 , 21 }

» B = { 4 , 8 , 12 , 16 , 20 }

» C = { 2 , 4 , 6 , 8 , 10 , 12 , 14 , 16 }

» D = { 5 , 10 , 15 , 20 }

✓ To find :

» A - B

✓ Solution :

A - B = { 3 , 6 , 9 , 12 , 15 , 18 , 21 } - { 4 , 8 , 12 , 16 , 20 }

» A - B = { 3 , 6 , 9 , 16 , 20 }

→ How to find A - B ?

» The elements in the set A must not be in the set B , Thats the value of A - B !!!

so here The Set C and D are not needed.

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→ More info :

» n(P U Q) = n(P) + (n(Q) – n (P ⋂ Q)

» For three sets P, Q, and R,

n( P U Q U R ) = n(P) + n(Q) + n(R) - n(P ⋂ Q) - n(Q ⋂ R) - n( P ⋂ R )