exponents prob 2....

[willbeatthegmat]

If 5^x=y, what is x?
a)y^2= 625
b)y^2= 15625

[sureshbala]

Could you please check the question (or the source) once again. Because in GMAT DS normally you will not have two contradictory statements.

[willbeatthegmat]

sorry...statement 2) y^3 = 15625

[marcusking]

a.) Given that the sqrt(625) is 25
that gives us that 5^x = 25 and thus x = 2
A is sufficient

b.) Given that 625 is 25^2 then 625 * 25 = 15625 and we know that
that gives us 5^x = 25 and thus x = 2
B is sufficient

So Each statement alone is sufficient

[willbeatthegmat]

that looks very simple n obvious...wat if y = -25....wat wud b d value of x in stat 1

[cjb]

a.) Given that the sqrt(625) is 25
that gives us that 5^x = 25 and thus x = 2
A is sufficient

But (-25)^2 also equals 625.

Not sure what that would mean in this case, as I don't know how to solve

5^x = -25


Nonetheless, I would answer B, not D.

[marcusking]

that looks very simple n obvious...wat if y = -25....wat wud b d value of x in stat 1

hmmmm........
I don't think this is possible. Since the base of the number is 5 and not -5 I don't think there is any power you can raise it to that would cause it to be -25. If we try raise it to any negative root we end up getting a decimal. If we try and raise it to any fraction or decimal of a power we still get a positive number.

Anyone else : :