Chapter 6.3, Problem 4WE

To determine

To write: an indirect proof of given conditional.

Answer to Problem 4WE

The correct first sentence of this indirect proof is: Assume that $x=y$ .

Explanation of Solution

Given information:

If $x^2\ne y^2$ , then $x\ne y$ .

Calculation:

Consider the following statement:

If $x^2\ne y^2$ , then $x\ne y$ .

Someone wants to write an indirect proof for this statement

There is need to write a first sentence assuming the conclusion of the proof is not true.

The correct first sentence of this indirect proof is: Assume that $x=y$ .