Subtracting fractions implies that the concept of unitizing
The unit is defined by the denominator (the bottom number).
The rules goes that
you cannot subtract fractions with different denominators!
( or, conversely, you can subtract fractions which have the same denominator only!
One common mistake first algebra learners have is to mistakenly subtract two fractions which have no common unit (or denominator) in this way:
1/6 - 1/2 = 1/4 (wrong !)
subtracting numerator and denominator as in a normal subtraction, like this:
8/5 - 2/3 = 6/3 (wrong !)
Instead, you must "do your maths"::
4/3 - 1/3 = 3/3 = 1 (correct!)
So, when subtracting fractions, mind the bottom numbers (the denominators)!
Are they the same? If positive just subtract the top numbers together and leave the bottom numbers as you found them!
603. The examples which a beginner should choose for prac-
Study and Difficulties of Mathematics (Chi-
source: Memorabilia mathematica; or, The philomath's quotation-book - Moritz, Robert Édouard, 1868-1940
STUDY AND RESEARCH IN MATHEMATICS
601. The first thing to be attended to in reading any algebraic
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