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
(X+1)^2-X^2=25
I.E 2X+1=25
2X=24
X=12
AND HENCE 69+N=144
N=75
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