Zeal Workbook: Mathematical Logic - First Order Logic

Question

How to write the last line of Qno. 19 - irrespective of whether the system has been armed the alarm should go off when there is fire

For Qno 20 I am getting iii) and iv) as true but answer is a) please check the 5th one 

Comments

they are not, in 4

y = 0 satisfies the equation but in 5

x = 0 satisfies the equation

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@utkarsh please see the question again you are telling about 6) the one

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i'm sorry i got confused i'll solve it in sometime

Answer 1

In 20th, 5th is true.

The statement says "For all x, there exists a y such that x + y = x - y."

This is true because we can take x to be any value and for any such value, y = 0 will always satisfy the proposition Q(x,y).

Comments

@goxul FOr every x there exist a y (y need not be same)

there exist a y  FOr every x (y is same for all x i.e is 0)

so both are different