Maths...how the hell do I work this out?

DanTheMan · 9 Oct 2011 at 14:13

I'm a maths noob who hasn't done it since GCSE and I've had to take a maths module as part of my degree. One of the exercises has this questions and I can't even understand where to begin ~.~ I understand the rules of indices but no idea what to do first in this question:

Evaluate: 4/5 (2/5)^-2

I'm hoping someone can shed some light on this...it's probably stupidly simple.

mod1fied · 9 Oct 2011 at 14:23

Well evaluate=solve

http://www.mathsisfun.com/algebra/negative-exponents.html
Using that you should be able to solve it

mufcmark · 9 Oct 2011 at 14:32

(5/2)^2 = 25/4

25/4*4/5 = 100/20
= 5

Explanation:

you should do the brackets to it's powers f first due to the rule of BEDMAS/BODMAS

B= Brackets
o= operations, squaring etc
d= divison
m= multiplication
a= adding
s= subtraction

2^-2 is the same as 1/2^2. 1/2 is the reciprocal of 2.

So in your case (2/5)^-2 is the same as (5/2)^2 which gives 25/4.

Then multiply the answer you got (25/4) by the 4/5 to get 100/20 which is the same as 5.

SheepBeast · 10 Oct 2011 at 00:05

mufcmark is correct