Answer
a. ) {-1,1}
b.) {1,2,3,4,5,6,7,8,9,10,11}
c.) {0,1,4,9,16,25,36,49,64,81}
d.) ∅
Work Step by Step
a.) {x|x is a real number such that $x^{2}$ = 1}
x can be -1 or 1 since $x^{2}$ = 1 So {-1,1} are the members of the set.
b.){x|x is a positive integer less than 12}
x can be 1,2,3,4,5,6,7,8,9,10,11 which is less than 12 So, {1,2,3,4,5,6,7,8,9,10,11}are the members of the set.
c.) {x| x is the square of an integer and x<100}
x can be 0,1,4,9,16,25,36,49,64,81 which is the square of an integer and less than 100. So, {0,1,4,9,16,25,36,49,64,81} are the members of the set.
d.) {x|x is an integer such that $x^{2}$ = 4}
Since there is no integer whose square is 4. So ∅ is the member of the set.