Question 271345
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5 and 4 have no factors in common so the LCD is just the product, namely 20.  Therefore:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ -\frac{4}{5}\ +\ \left(-\frac{3}{4}\right)]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ -\frac{16}{20}\ +\ \left(-\frac{15}{20}\right)]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \frac{-16\,+\,\left(-15\right)}{20}]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ -\frac{31}{20}]


All of which makes good sense because:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ -\frac{4}{5}\ =\ -0.80]


and


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ -\frac{3}{4}\ =\ -0.75]


and


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ -0.80\ +\ (-0.75)\ =\ -1.55]


and


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ -\frac{31}{20}\ =\ -1.55]


John
*[tex \LARGE e^{i\pi} + 1 = 0]
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