bdevas01 wrote:I was on platinumgmat.com, looking over their quantitative tutorials and I believe I have found an error, but I'd just like confirm it with the community.

The tutorial states the following:

"If x+2 < y+2 is multiplied by -1 on both sides, the result is not -2-x < -y-2. Instead, the result is -2-x > -y-2. "

I don't understand why the 'x' and the '2' on the left-hand side of the inequality have changed order. I believe it's a typo, but maybe I'm missing something.

What do you guys think?
The direct link to the site is: https://www.platinumgmat.com/gmat_study_ ... equalities

Thanks in advance for all posts!

hello devas

the operation is correct
in inequalities whenever u multiply or divide bth side by -1 the sign reverses.....

to understand this just consider x and y are int such that x<y ; now multiply bth side by -1 result will be -x>-y
for eg
x=2 and y=10
2<10
but -2>-10
hence multiplying -1 will rsult in change of sign
same is true with div....

moreover when x>y
we can not say x/Y>1
bcoz for -x and -y result will be opp...

but we can say x-y>0

Thank you for your reply but that was not my question. I understand that the sign changes but why do the x and the 2 switch places?

bdevas01 wrote:Thank you for your reply but that was not my question. I understand that the sign changes but why do the x and the 2 switch places?

it doesn't matter in which order they are. As long as they are on the same side.

-x-2 is the same as -2-x

That's true, I didn't catch that but now that you point it out, it makes sense. Subtracting a number from a negative number is the same thing as adding a number to a positive number (with the exception that one will yield a negative number and the other a positive number).

I'm just curious to know why the two numbers were flipped in the first place. Any ideas?

well,the catch in such questions is that you just have to put some values of x and y...suppose x is 2 and y is 3 ....then x+2 (4)<y+2(5).......but on the negative number line -4>-5...thus this is an objective way of getting to the answer.....and a pretty simple way too as it takes just 3-5 seconds to figure out

bdevas01 wrote:That's true, I didn't catch that but now that you point it out, it makes sense. Subtracting a number from a negative number is the same thing as adding a number to a positive number (with the exception that one will yield a negative number and the other a positive number).

I'm just curious to know why the two numbers were flipped in the first place. Any ideas?

well,flipping the numbers is just a way of confusing you and decreasing your speed......just keep your concepts clear

Got it.

Thanks for clearing it all up guys!