the cube root of x + y^2

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sanju09: GMAT Instructor; Posts: 3650; Joined: Wed Jan 21, 2009 4:27 amFollowed by: 80 members; Location: India; Thanked: 267 times; GMAT Score:760

by sanju09 » Fri Oct 15, 2010 10:10 pm

If x and y are positive integers, is the cube root of x + y^2 an integer?

[1] x = y^2 (y - 1).

[2] x = 2.

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Source: Beat The GMAT — Data Sufficiency | Fri Oct 15, 2010 10:10 pm

pradeepkaushal9518: Legendary Member; Posts: 1309; Joined: Wed Mar 17, 2010 11:41 pmFollowed by: 5 members; Thanked: 33 times

by pradeepkaushal9518 » Sat Oct 16, 2010 12:17 am

x,y positive intergers , cube root of x+y^2 an integer?

1.x=y^2(y-1)

x=y^3-y^2

x+y^2=y^3-y^2+y^2=y^3 so cube root =y y is interger so suff

2.x=2

no idea about y so not suff

imo A

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