The Student Room Group
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>

Positive and Negative after squaring??

I am currently preparing for my A level math c1, and am slightly confused on the idea of when to put a +- when squaring. there seems to be some cases when it is ignored, and others when it is important.

for example 81^1/2 = +- 9, or Just 9?

Iv heard that it is considered to be positive, if nothing has been mentioned. but there has been a few questions in the past where I can been caught out. Any advise on remembering this?

Kind regards
The answer for the square root always contains two values which can be positive or negative.You have to consider both the values unless otherwise stated.For example if you are working with a time sum you can ignore the negative value since time won't take a negative value(you'll get to know when you are doing mechanics).And no need to remember that!
Original post by Cloudymath
I am currently preparing for my A level math c1, and am slightly confused on the idea of when to put a +- when squaring. there seems to be some cases when it is ignored, and others when it is important.

for example 81^1/2 = +- 9, or Just 9?

Iv heard that it is considered to be positive, if nothing has been mentioned. but there has been a few questions in the past where I can been caught out. Any advise on remembering this?

Kind regards


For C1 maths exams
If you are evaluating a power of a given number you are only being asked for the positive square root
Square root of 81 = 9
If you are solving an equation the positive and negative solutions are required unless excluded by the question
or example x^2 = 81, x = + or - 9


Posted from TSR Mobile

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you