Are the following pair of sets equal? Give reasons :

(i) A = {2, 3}, B = {x : x is solution of x² + 5x + 6 = 0}

(ii) A = {x : x is a letter in the word FOLLOW}, B = {y : y is a letter of word WOLF}

Solution

(i) A = {2, 3}
B = { x : is solution of x² + 5x + 6 = 0}

Now, x² + 5x + 6 = 0 $rightwards double arrow$ (x+2)(x+3) = 0

$rightwards double arrow$ x = -2, x = -3 $rightwards double arrow$ B = {-2, -3}
Clearly, $space space space space space space space space space space space straight A space not equal to space straight B$

(ii) A = { x: x is a letter in the word FOLLOW

$rightwards double arrow$ A = { F, O, L, W}
Also, B = { y : y is a letter of the word WOLF}
$rightwards double arrow$ B = { W, O, L, F}
Hence, A = B.