Re: OT: Another SAT Question of the Day

On Sep 19, 10:16 pm, R H Draney <dadoc...@xxxxxxxxxxx> wrote:
Robert Cohen filted:







On Sep 18, 2:32=A0pm, Sally <SallyDr...@xxxxxxx> wrote:
On Sep 18, 1:32=A0pm, Robert Cohen <robtco...@xxxxxxx> wrote:

On Sep 18, 11:01=A0am, foxyscrib...@xxxxxxxxx wrote:

Note: =A0Those 2s should be up in the corner. =A0Didn't copy and past=
e
that way.
I already chose the wrong answer....apparently I'm not alone - only
29% have gotten it right so far.

If (x + y)2 =3D x2 + y2, which of the following statements must also =
be
true?

x =3D 0
(x =96 y)2 =3D x2 + y2
xy =3D 0

A. =A0 =A0 None
B. =A0 =A0 I only
C. =A0 =A0 II only
D. =A0 =A0 III only
E. =A0 =A0 II and III

my take

first i work the equation as per this:

2X + 2Y =3D X squared + Y squared

2X -X squared =3D Y squared -2Y

then i read & fret over the tricky question

the answer is A or D

I'll guess D (with a small hedge bet on A)- Hide quoted text -

- Show quoted text -

A

Sally

I re-read the question again, and thus re-read the cautionary thing
about "2s"

No wonder the problem was a problem

So just for the heckuvit, I'll try it again

(x + y) squared =3D x squared + y squared

x square  + xy + y squared =3D x squared + y squared

xy=3D0

still tricky enough, tho now I pick E

Using the above as my justification, I say that the answers to all SAT questions
are null and void if Foxy has any problems with the character set....r

--
A pessimist sees the glass as half empty.
An optometrist asks whether you see the glass
more full like this?...or like this?- Hide quoted text -

- Show quoted text -

E it is (again...the following 2s should be levitating..):

Correct!
Here's Why:

The quantity (x + y)2 can be expressed as x2 + 2xy + y2. If (x + y)2 =
x2 + y2, then 2xy = 0 and xy = 0. Since xy = 0, either x = 0 or y = 0
or both. Therefore, statement III must be true, but statement I, x =
0, is not always true. For statement II, you can write (x – y)2 = x 2
– 2xy + y2, and since xy = 0, it follows that (x – y)2 = x2 + y2.
Therefore, both statements II and III must be true.


Difficulty: Hard (No kidding - only 29% got it right)
.

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