Resposta:
a)
49
−
64
7−8
−1
\begin{gathered}b)15 - \sqrt{100} \\ 15 - 10 \\ \color{red}5\end{gathered}
b)15−
100
15−10
5
\begin{gathered}c) - 1 + 81 - \sqrt{9} \\ - 1 + 81 - 3 \\ 80 - 3 \\ \color{red}77\end{gathered}
c)−1+81−
9
−1+81−3
80−3
77
\begin{gathered}d) \sqrt{400} - \sqrt{900} \\ 20 - 30 \\ \color{red} - 10\end{gathered}
d)
400
−
900
20−30
−10
