Question

for each of the following, check that a-b is not equal to b-a. a=13/15 and b=-7/13​

Answer 1

$here \\ a = \frac{13}{15} \\ b = \frac{ - 7}{13} \\ \\ so \\ \: \: \: \: \: a - b \\ = \frac{13}{15} - \frac{ (- 7)}{1 3 } = \frac{13}{15} + \frac{7}{13} \\ = \frac{13 \times 13 + 7 \times 15}{13 \times 15} = \frac{169 + 105}{195} \\ = \frac{274}{195} \\ \\ and \\ \: \: \: \: \: b - a \\ = \frac{ - 7}{13} - \frac{13}{15} = \frac{( - 7) \times 15 - 13 \times 1 3}{13 \times 15} \\ = \frac{ - 105 - 169}{195} \\ = - \frac{274}{195}$

hence, a - b ≠ b - a