Question

is this null set? justify.
1.A={x:x=4 and 3x=9}
2.B={x:x+5=5,x(belong to)N

Answer 1

Answer:

yes Set A is null set

bcoz, 3x = 9

putting x=4 in given equation,

3×4 = 12 hence, Set A is null set

x+5 = 0 this equation satisfied only if x = 0

but here condition is x = N natural number and zero is not natural number

so Set B is null set.

Answer 2

Answer:

1 . 4+3=7

7×9=64

a=7

b=9

n=64