Proofs Trial Q (1 Viewer)

[krypticlemonjuice]

Can someone please explain why the answer to this question is D, and none of the others?

 

[SadCeliac]

all other options are wrong by a counterexample

A) if x is 0, there is no possible y to make it true
B) not sure what reasoning tbh - but I think it's something about the wording...? (@carrotsss help)
C) if y is 0, there is no possible x to make it true

D is true because no matter what x you have, there will be a y = 10-x that makes it true

 

[its_ace21]

all other options are wrong by a counterexample

A) if x is 0, there is no possible y to make it true
B) not sure what reasoning tbh - but I think it's something about the wording...? (@carrotsss help)
C) if y is 0, there is no possible x to make it true

D is true because no matter what x you have, there will be a y = 10-x that makes it true

i agree

 

[cossine]

all other options are wrong by a counterexample

A) if x is 0, there is no possible y to make it true
B) not sure what reasoning tbh - but I think it's something about the wording...? (@carrotsss help)
C) if y is 0, there is no possible x to make it true

D is true because no matter what x you have, there will be a y = 10-x that makes it true

For B, arbitrarily choose any value of x let say x = 2. Since it needs to hold for all y this means that 2 + y = 10 for all y which is clearly False.

 

[carrotsss]

(@carrotsss help)

keep in mind that the order matters for these questions, B is implying that there is a singular x value such that no matter what y value you select, xy=10, which is clearly impossible