Consider a proposition given as : “ x ≥ 6, if x2 ≥ 5 and its proof as:
If x ≥ 6, then x2 = x.x ≥ 6.6 = 36 ≥ 25
Which of the following is correct w.r.to the given proposition and its proof?
(a)The proof shows the converse of what is to be proved.
(b)The proof starts by assuming what is to be shown.
(c)The proof is correct and there is nothing wrong.
(A) (a) only
(B) (c) only
(C) (a) and (b)
(D) (b) only
Answer: (C)
Explanation: “ x ≥ 6, if x2 ≥ 5 and its proof as:
If x ≥ 6, then x2 = x.x ≥ 6.6 = 36 ≥ 25
it is clear from the above statement that proof starts by assuming what is to be shown and it is clear that the proof shows the converse of what is to be proved hence the proof is not correct.
Statement (a) and (b) are correct but (3) statement is not correct.
So, option (C) is correct.
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