Simplify the operation
Reduce (simplify) the fractions to their lowest terms equivalents:
- To reduce a fraction to the lowest terms equivalent: divide both the numerator and denominator by their greatest common factor, GCF.
The fraction: - 82/18
- The prime factorizations of the numerator and denominator:
- 82 = 2 × 41
- 18 = 2 × 32
- Multiply all the common prime factors: if there are repeating prime factors we only take them once, and only the ones having the lowest exponent (the lowest powers).
- GCF (82; 18) = 2
- 82/18 = - (82 ÷ 2)/(18 ÷ 2) = - 41/9
The fraction can also be reduced without calculating GCF; factor the numerator and denominator and cross out all the common prime factors:
- 82/18 = - (2 × 41)/(2 × 32) = - ((2 × 41) ÷ 2)/((2 × 32) ÷ 2) = - 41/9
The fraction: - 85/23
- 85/23 is already reduced to the lowest terms.
The numerator and denominator have no common prime factors:
- 85 = 5 × 17
- 23 is a prime number.
- GCF (85; 23) = 1
Calculate the common denominator
The common denominator is nothing else than the least common multiple (LCM) of the denominators of the fractions.
To calculate the LCM, we need the prime factorization of the denominators:
9 = 32
23 is a prime number.
Multiply all the unique prime factors: if there are repeating prime factors we only take them once, and only the ones having the highest exponent (the highest powers).
LCM (9, 23) = 32 × 23 = 207