A rectangular circuit board is designed to have width w inch

Suppose,

L= 2 in, W= 4 in

Then Area=8 in and Perimeter = 12 inches, let us test the equations

(A) w^2 + pw + k = 0 16+48+8 not equal to zero
(B) w^2 - pw + 2k = 0 16-48-16 not equal to zero
(C) 2w^2 + pw + 2k = 0 32+48+16 not equal to zero
(D) 2w^2 - pw - 2k = 0 32-48-16 not equal to zero
(E) 2w^2 - pw + 2k = 0 32-48+16 equals zero

Option E

Also we could have eliminated options A and C since if the equations have to be equal to zero, then we need at least one expression as negative.


Hope it helps!

[email protected] wrote:Hi guerrero,

I'm going to give you a nudge and have you try this question again:

1) Draw a picture of a rectangle.
2) TEST VALUES. Pick a value for the width and the length
3) Calculate anything else that you need to calculate

GMAT assassins aren't born, they're made,
Rich

thanks Rich , I used height as "H" & Width as "W" . Equated the assumed value( H )in Perimeter and Area formula and got the required equation in ~1 Min .

Did not realize it was that simple

Let Length =a width = w (given)

hence perimeter = 2*(a+w)=p ----(A)
areq= a*w=k
>> a= k/w -----------(B)

2* ((k/w)+w)=p using (B)
> 2W^2 -pw+ 2k=0

hence E

guerrero wrote:A rectangular circuit board is designed to have width w inches, perimeter p inches, and area k square inches. Which of the following equations must be true?

(A) w^2 + pw + k = 0
(B) w^2 - pw + 2k = 0
(C) 2w^2 + pw + 2k = 0
(D) 2w^2 - pw - 2k = 0
(E) 2w^2 - pw + 2k = 0

OAE

Since w,p, and k are all positive, eliminate A and C.
p = 2w + 2l (l is the length)
k = lw
2k = (2l) w
2k = (p - 2w)w
2k = pw - 2w^2
2w^2 - pw + 2k = 0

Choose E

Cheers