Math Is Fun Forum

Kiran

Member

Registered: 2006-11-15

Posts: 177

Right or Wrong

"Let "p" represent "the area of rectangle ABCD is 50 square inches."
Let "q" represennt "the perimeter of rectangle ABCD is 30 inches."
Llet "r" represent "the length of rectangle ABCD is twice the width."

p = area of rectangle is 50sqin
q = perimeter of the rectangle is 30in
r = ength of the rectangle is twice width

THEY ASKED THIS QUESTION:
Use symbols to represent the conjunction below:
THE AREA OF RECTANGE ABCD IS 50 SQUARE INCHES AND ITS LENGTH IS NOT TWICE ITS WIDTH.
I wrote:

p = area of the rectange ABCD is 50 sq in
v = and
r = length of the rectangle ABCD is twice the width
~r = length of the rectangle ABCD is not twice the width
pv~r "

Right or wrong?
if right than why did my teacher say its wrong?

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Zhylliolom

Real Member

Registered: 2005-09-05

Posts: 412

Re: Right or Wrong

Did you write it as

If you did, that means "p OR not r". To say "p AND not r" in symbols you want to flip your "v" over:

Last edited by Zhylliolom (2006-12-02 15:28:39)

Kiran

Member

Registered: 2006-11-15

Posts: 177

Re: Right or Wrong

ok thanks

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Kiran

Member

Registered: 2006-11-15

Posts: 177

Re: Right or Wrong

ok i have 2 more questions to the top information:
"Let "p" represent "the area of rectangle ABCD is 50 square inches."
Let "q" represennt "the perimeter of rectangle ABCD is 30 inches."
Llet "r" represent "the length of rectangle ABCD is twice the width."

p = area of rectangle is 50sqin
q = perimeter of the rectangle is 30in
r = ength of the rectangle is twice width

These Are The Two Questions..again teach said it is wrong so what can  i do now?

If rectangle ABCD is 9 inches long and 6 inches wide, what is the truth value of the disjunction q v  ~p ?
I wrote :
q = 9
p = 6
~ p = -6
pv ~ q = 9 + (-6)
9 - 6
3 it is  positive value

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Suppose rectangle ABCD is 12.5 inches ong and 4 inches wide. What is the truth vaue of the conditional p -->  r ?
I wrote :
ength = p = 12.5
width = r = 4
12 is always greater than 4
p > r
12.5 > 4 is the true value

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Monox D. I-Fly

Member

From: Indonesia

Registered: 2015-12-02

Posts: 2,000

Re: Right or Wrong

ok i have 2 more questions to the top information:
"Let "p" represent "the area of rectangle ABCD is 50 square inches."
Let "q" represennt "the perimeter of rectangle ABCD is 30 inches."
Llet "r" represent "the length of rectangle ABCD is twice the width."

p = area of rectangle is 50sqin
q = perimeter of the rectangle is 30in
r = ength of the rectangle is twice width

These Are The Two Questions..again teach said it is wrong so what can  i do now?

If rectangle ABCD is 9 inches long and 6 inches wide, what is the truth value of the disjunction q v  ~p ?
I wrote :
q = 9
p = 6
~ p = -6
pv ~ q = 9 + (-6)
9 - 6
3 it is  positive value

`````````````````````````````````````````````````````````````
Suppose rectangle ABCD is 12.5 inches ong and 4 inches wide. What is the truth vaue of the conditional p -->  r ?
I wrote :
ength = p = 12.5
width = r = 4
12 is always greater than 4
p > r
12.5 > 4 is the true value

Ugh... It's not that simple. For the first question:

If rectangle ABCD is 9 inches long and 6 inches wide, what is the truth value of the disjunction q v  ~p ?

perimeter = 2 x (9 + 6) = 2 x 15 = 30 inches, so q is True because it said that the perimeter is 30 inches.
area = 9 x 6 = 54 square inches, so p is False because it said that the area is 54 square inches.
q v ~p
= True v ~False
= True v True
= True

For the second question:

Suppose rectangle ABCD is 12.5 inches ong and 4 inches wide. What is the truth vaue of the conditional p -->  r ?

area = 12.5 x 4 = 50 inches, so p is True because it said that the area is 50 inches.
12.5 is not twice of 4, so r is False because it said that the length is twice the width.
p --> r
= True ---> False
= False

I hope you got it after a decade.

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May his adventurous soul rest in peace at heaven.