exponents are killing me

[Wakka Wakka]

From a question in the MH GMAT practice test...from step 1 to step 2 we loose 5^13 which becomes (5-1)...can someone explane this to me please? THanks


1.) 5^12 – 6(5^13 – 5^12) =
2.) 5^12 – 6[5^12(5 – 1)] =
3.) 5^12 – 6(5^12)(4) =
4.) 5^12(1 – 24) =
5.) (-23)5^12.

[Wakka Wakka]

I guess it couldn't hurt to post the question also...

A, B, C, D, E, F, G, and H are all integers, listed in order of increasing size. When these numbers are arranged on a number line, the distance between any two consecutive numbers is constant. If G and H are equal to 5^12 and 5^13, respectively, what is the value of A?

[sudhir3127]

5^12 – 6(5^13 – 5^12)

5^13 canbe written as 5^12*5 ( as the bases are same powers can be added)

hence it will be 5^12- 6( 5^12*5- 5^12)
5^12- 6.5^12( 5-1)
5^12 – 6(5^12)(4)

5^12(1 – 24)

hope its clear now.. let meknow if u still have a doubt..

[Wakka Wakka]

I really appreciate it thank you...also thank for the quick reply.

[Wakka Wakka]

I was just going over the formula and I get that we can take 5^13 to 5^12*5, but how do we get one 5^12 to become 1?

Thanks

[Wakka Wakka]

Nevermind...haha, just saw it...really appreciate it though, THANKS!!!