![tystevens9943](/avatars/23026.jpg)
tystevens9943
12.07.2019 •
Mathematics
Identify the error or errors in this argument that supposedly shows that if ∃xp (x) ∧ ∃xq(x) is true then ∃x(p (x) ∧ q(x)) is true. 1. ∃xp (x) ∨ ∃xq(x) premise 2. ∃xp (x) simplification from (1) 3. p (c) existential instantiation from (2) 4. ∃xq(x) simplification from (1) 5. q(c) existential instantiation from (4) 6. p (c) ∧ q(c) conjunction from (3) and (5) 7. ∃x(p (x) ∧ q(x)) existential generalization
Solved
Show answers
More tips
- C Computers and Internet How to Create a VKontakte App: A Detailed Guide...
- L Leisure and Entertainment When will Maslenitsa start?...
- F Food and Cooking Discovering the Mysterious Fruit of Feijoa...
- B Business and Finance How to Open an Online Store? A Detailed Guide for Beginners...
- W Work and Career How to Write a Resume That Catches the Employer s Attention?...
- C Computers and Internet Е-head: How it Simplifies Life for Users?...
- F Family and Home How to Choose the Best Diapers for Your Baby?...
- F Family and Home Parquet or laminate, which is better?...
- L Leisure and Entertainment How to Properly Wind Fishing Line onto a Reel?...
- L Leisure and Entertainment How to Make a Paper Boat in Simple Steps...
Answers on questions: Mathematics
- M Mathematics Anna has$600 in a savings account that earns 8%interestperyear..Howmuchwillshehavein5years?...
- M Mathematics HURRY UP AND PLZ ANSWER,THIS IS FOR A GRADE AND I NEED TO PASS, I WILL GIVE BRAINLIEST whats 2+2?? :p...
- M Mathematics The measure of one angle of a right triangle is 56∘ more than the measure of the smallest angle. Find the measure of the smallest angle....
- M Mathematics Guy is being transferred from his home...
- M Mathematics EASY MATH PLEASE HELP! : ) NO LINKS PLEASE! EXPLANATION REQUIRED! I WILL GIVE BRAINLIEST! Kay has three pieces of luggage on to take on the trip. The total amount...
- M Mathematics Select ALL the true statements. There is more than one answer. It is always...
- M Mathematics Which of the following is the circumference of a circle with a radius of 6 centimeters? C=ad...
- M Mathematics Please helppp not trying to fail...
- M Mathematics Which digit tells you whether a number will be rounded up or down?...
- M Mathematics Does anyone know any good xxx sites.Will give Brainliest and plz don t report me....
Ответ:
The mistake lies in steps 3 and 5.
In fact, you know that there exists some element that satisfies p(x), and some element that satisfies q(x), but you can't assume that the same element satisfies p(x) and q(x) at the same time.
So, you are only allowed to say
p(c) existential instantiation from (2)
q(d) existential instantiation from (4)
and so you can't do the conjunction in step 6 anymore.
Here's an example: if you follow this logic, you would say something like:
"There exists a person who is born in Italy and there exists a person who is born in the USA. Therefore, there exists a person who is born in both Italy and the USA"
which is clearly false: altought there exists a person for each proposition, they are not the same person.
This is even easier if q is the negation of p:
"There exists a number greater than 10, and there exists a number lesser than 10. Therefore, there exists a number that is greater than and lesser than 10 at the same time"
which is clearly absurd
Ответ:
5x-20°=180°
5x=200°
x=40°
Angle X=3x+19°
Angle X=139°. As a result, B is the correct answer. Hope it help!