Q10,p2,J15.Consider a proposition given as:

x>=6 if x²>=25 and its proof as :

if x>=6 then x.x=36>=25.

Which of the following is correct  wrt to given proposition and its proof.?

1.       The proof shows the converse of what is to be proved.

2.       Proof starts by assuming what is to be shown.

3.       Proof is correct and there is nothing wrong.

Options

A)     1 only    B)3 only                C) 1 and 2.           D)2 only.

Answer .B.

Explanation.

Proof says any number greater than or equal to 6, its  square is greater than or equal to 25.

6x6>25. 7x7>25-------.

Proposition 1 Fails because it does not prove that  number (6,7,8---) square is not greater than 25.

Proposition 2 fails because there is no requirement of assumption as numbers are already given.

Proposition 3 is correct.