Tricky SAT Question (algebra)?

Question

Hey everyone,

Just would like to know everyone's thoughts on this one. What do you think would be the best way to solve for numeric value of k:

(n/n-1) * (1/n) * (n/n+1) = (5/k)

I can't seem to get it--sure I'm overlooking something simple. Thanks!

Answer 1

You just have to work out what the left side is in it's simplest terms and then solve for K. Unless you have the number that n equals, it's going to come out in terms of n.

The answer is k = 5(n^2 -1)/n

Answer 2

A tricky question it is indeed, yet not an unsolvable one. While the High-school-math-instinct is to simplify this equation using known algebric identities and stuff, I think the easiest and most efficient one is to put in real numbers instead of n.
Nevertheless, the tricks do not end there. Seeing as we aren't allowed 2 divide by zero, lazy minds tempted to put in n=1 would be cruelly dissappointed, as n/n-1 would then equal 1/0, which is, at least, not particularly brilliant. Same goes, therefore, for (-1) and zero itself. So let's put in 2!!!. The question is very hard not to solve correctly from there:
(2/1)*(1/2)*(2/3)=5/k
4/6=5/k and k=7.5.
This way of solving is very acceptable in questions where you don't have to show how u solved the q, but rather choosing the right answer (most quickly, I might add). Finally, I must mention that anybody thinking this is quite a cheeky way of solving which makes him feel like he's just tricked the trick question itself, then in that case he will not encounter any disagreement from my side... ;-)

Answer 3

The first part of the equation = 0
(n/n - 1) = (1-1) = 0

so the whole thing is

0 = 5/k

There is no value for k that will satisfy this equation.

Answer 4

cancel the n in the first fraction with the n in the second and you get

1/(n-1)*n/(n+1)=5/k multiply the denominators

n/(n^2-1)=5/k cross multiply

nk=5(n^2-1) divide by n

k= 5(n^2-1)/n

Answer 5

So Simple, Just put the values for n and find the value of k.
The simplified equation for the given expression might be:
k=5(n-1/n).

Answer 6

N/n-1 times 1/n is 1/n-1. Take that, times n/n+1 = 5/k

that equals n/(n-1)(n+1) = 5l

rearrange:

K = 5(n-1)(N+1)/n

Answer 7

Retake the SAT and additionally take the ACT. additionally take some SAT II difficulty exams, a minimum of three. Which try you're able to take relies upon on the college you're finding at. In different words, some choose one over the different. To get the superb probabilities of stepping right into a school of your selection, take the two. could the Lord Jesus Christ bless you.

Answer 8

First, simplify the left side:
(n^2) / (n(n+1)(n-1)) = 5/k
n / [(n+1)(n-1)]=5k

multiply both sides by k
k[(n) / ((n+1)(n-1))]=5

then multiply both sides by the reciprocal of the fraction without k
k = 5((n+1)(n-1)) / (n)

Answer 9

k=5/(n/n-1)/(n/n+1)/(1/n)

Answer 10

Firstly you need to simplify the bit on the left. Then you'll find it really easy to solve the equation in terms of 'n'.