exponent problem

[josephcho77]

99,999^2 - 1^2 =

A. 10^10 - 2
B. (10^5 – 2)^2
C. 10^4(10^5 – 2)
D. 10^5(10^4 – 2)
E. 10^5(10^5 – 2)

Can anyone help to solve above problem? Thanks!

[samirpandeyit62]

99,999^2 - 1^2

= (100000-1)^2 -1

= 100000^2 +1 - 200000 -1

= 100000^2 - 200000

= 100000(100000 -2)

= 10^5(10^5 -2)

[me4mba]

Or x^2 – y^2 = (x+y)(x-y). So you have (99,999+1)(99,999-1) which is (100,000)(99,998) Which is also (10^5)(10^5 – 2).

[lawalx]

hi samir

where can i learn to factorize exponents like u jst did. pls hlp

[samirpandeyit62]

Hi lawalx,
I've not looked specifically into any thing for exponents but I think that Kaplan GMAT 800 is good for maths concepts.