Sign in
Please select an account to continue using cracku.in
↓ →
Join Our JEE Preparation Group
Prep with like-minded aspirants; Get access to free daily tests and study material.
Consider the following two propositions :
$$P_1:\sim(p\to\sim q)$$
$$P_2:(p\land\sim q)\land(\sim p\lor q)$$
If the proposition $$p\to(\sim p\lor q) $$ is evaluated as FALSE, then
For an implication
$$A\to B$$
to be FALSE,
$$A=\text{TRUE},\qquad B=\text{FALSE}$$
Hence,
$$p=\text{TRUE}$$
and
$$\sim p\lor q=\text{FALSE}$$
Now, an OR statement is FALSE only when both parts are FALSE.
Therefore,
$$\sim p=\text{FALSE},\qquad q=\text{FALSE}$$
Thus,
$$p=\text{TRUE},\qquad q=\text{FALSE}$$
Now,
$$P_1=\sim(p\to\sim q)$$
Since
$$p=\text{TRUE},\qquad \sim q=\text{TRUE}$$
we get
$$p\to\sim q=\text{TRUE}$$
Hence,
$$P_1=\sim(\text{TRUE})=\text{FALSE}$$
Also,
$$P_2=(p\land\sim q)\land(\sim p\lor q)$$
$$=(\text{TRUE}\land\text{TRUE})\land(\text{FALSE}\lor\text{FALSE})$$
$$=\text{TRUE}\land\text{FALSE}$$
$$=\text{FALSE}$$
Therefore, both $$P_1$$ and $$P_2$$ are FALSE.
Create a FREE account and get:
Educational materials for JEE preparation