Question 323 Data Sufficiency 2018 GMAT Official Guide Video explanation: If the positive integer n is added to each of the integers 69,…

Sudhanshu Singh says May 28, 2019 at 8:07 AM (X+1)^2-X^2=25 I.E 2X+1=25 2X=24 X=12 AND HENCE 69+N=144 N=75 Reply

GMAT Quantum says June 6, 2019 at 4:49 PM Hi Sudhanshu, That is great that you used the difference of squares identity to speed up the algebra. This is exactly what the GMAT writers want students to do. I didn’t do that in this particular problem, but this is how you can speed up things. Dabral Reply

Sudhanshu Singh says

(X+1)^2-X^2=25

I.E 2X+1=25

2X=24

X=12

AND HENCE 69+N=144

N=75

GMAT Quantum says

Hi Sudhanshu,

That is great that you used the difference of squares identity to speed up the algebra. This is exactly what the GMAT writers want students to do. I didn’t do that in this particular problem, but this is how you can speed up things.

Dabral