Question

unit: rational expressions
progress:
the movement of the progress bar may be uneven because questions can be worth more or less (including zero) depending on your answer
subtract. state the difference in simplest form.
$\frac{7}{4m} - \frac{4}{3n}$
$\frac{3}{4m - 3n}$
$\frac{7m - 3n}{3mn}$
$\frac{1}{4mn}$
$\frac{21n - 16m}{12mn}$

Explanation:

Step1: Find a common denominator

The denominators are \(4m\) and \(3n\), so the common denominator is \(12mn\).

$$ \frac{7}{4m} - \frac{4}{3n}=\frac{7\times3n}{4m\times3n}-\frac{4\times4m}{3n\times4m} $$

Step2: Simplify the numerators

Simplify the numerators of the two fractions:

$$ \frac{21n}{12mn}-\frac{16m}{12mn} $$

Step3: Subtract the numerators

Subtract the numerators while keeping the common denominator:

$$ \frac{21n - 16m}{12mn} $$

Answer:

\(\frac{21n - 16m}{12mn}\) (which corresponds to the option \(\frac{21n - 16m}{12mn}\))