Question

2x10^-4 - 1x10^-5 show work. I got an answer of 1.9x10^-4,

Answer 1

$\bf \left.\qquad \qquad \right.\textit{negative exponents}\\\\ a^{-{ n}} \implies \cfrac{1}{a^{ n}} \qquad \qquad \cfrac{1}{a^{ n}}\implies a^{-{ n}} \qquad \qquad a^{{{ n}}}\implies \cfrac{1}{a^{-{{ n}}}}\\\\ -------------------------------$

$\bf 2\times 10^{-4}-1\times 10^{-5}\implies 2\cdot \cfrac{1}{10^4}-1\cdot \cfrac{1}{10^5}\impliedby \begin{array}{llll} \textit{using the LCD}\\ of~10^5 \end{array} \\\\\\ \cfrac{2}{10^4}-\cfrac{1}{10^5}\implies \cfrac{(10\cdot 2)~-~(1\cdot 1)}{10^5}\implies \cfrac{20-1}{10^5}\implies \cfrac{19}{10^5} \\\\\\ 19\cdot \cfrac{1}{10^5}\implies 19\times 10^{-5}$

Answer 2

2 • 10^-4 – 1 • 10^-5 =
0.0002 – 0.00001 = 0.00019
1.9 • 10^-4