Question

If A = {1,2,3}, B = {3,4,5), then n(A x B) =
b) 9
a) 3
c) 6
d) 8
​

Answer 1

Answer:

n(A×B)=(1,3),(1,4),(1,5),(2,3),(2,5)(2,4),(3,3),(3,4),3,5)=n(A×B)==9

Answer 2

It's clear that..

n(A) = 3

n(B) = 3

Note the formula,

Let A and B be two non empty sets. Such that, n(A) = p and n(B) = q. Then, n(A×B) = n(p) × n(q).

So, n(A×B) = n(A) × n(B)

n(A×B) = 3 × 3

n (A×B) = 9

Now lets prove this,

A×B = { ( 1,3 ) , ( 1,4 ) , ( 1,5 ) , ( 2,3 ) , ( 2,4 ) , ( 2,5 ) , ( 3,3 ) , ( 3,4 ) , ( 3,5 ) }

Therefore, n(A×B) = 9

Hence proved..

Hope that helps u :)

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