manhattan exponents

resilient · Posted: Mon Mar 03, 2008 12:20 pm Post subject: manhattan exponents

(226)^2-(225)^2= ?

My approach: (225+1)^2=(225)^2= 225's cancel out and I am left with 1^2= 1

My answer is wrong

qa is 451. WHat did I do wrong?

smar83 · Posted: Mon Mar 03, 2008 12:47 pm Post subject:

No, you do not do it that way.

The correct approach is to use the formula : (a^2-b^2) = (a+b)(a-b).

Just substitute your values and you would get:

a=226
b=225,

(226+225)(1)

your answer is 451.

smushkas · Posted: Mon Mar 03, 2008 12:48 pm Post subject:

You should have done by ==> (a + b )^2 = a^2 + 2ab + b^2
( 226 )^2 - ( 225 )^2 = [ (225+1)^2 ] - (225)^2 = [ 225^2 + 225 + 225 + 1 ] - (225)^2 =
= 225^2 + 451 - 225^2 = 451

Hope it is clear!

resilient · Posted: Mon Mar 03, 2008 10:45 pm Post subject: hmm

so this question hinges on seeing the 225+1 but also to the see the common factor ?