Question

Which of the following disjunctions is false?6 · 2 = 11 or 3 + 5 = 85 - 3 = 2 or 3 · 4 = 123 + 4 = 9 or 5 · 2 = 112 · 3 = 6 or 4 + 5 = 10

Answer 1

Let us begin by defining a disjunction

Disjunction, in logic, relation or connection of terms in a proposition to express the concept “or”; it is a statement of alternatives (sometimes called “alternation”).

In disjunction, the compound proposition is false only if both statements (disjuncts) are false.

(i)

$6\text{ . 2 = 11 or 3 + 5 = 8}$

The first statement is false and the second is true

Answer: True

(ii)

$5\text{ -3 = 2 or 3 . 4 = 12}$

The first statement is true and the second is also true

Answer: True

(iii)

$3\text{ + 4 = 9 or 5 .2 = 11}$

The first statement is false and the second is false

Answer : False

(iv)

$2.3\text{ =6 or 4 + 5 =10}$

The first statement is true and the second is false

Answer: True

Hence, the disjunction that is false is Option 3