Union and intersection of intervals

Question

B  and C are sets of real numbers defined as follows.

B={z| z< 3}

C={z| z< 9}

Write ∪BC

 and ∩BC

 using interval notation.

If the set is empty, write ∅

.

Answer 1

B union C = {z|z<3}

B intersection C ={z|z</=9} where B and C overlap