1,Tính:
a) (-53)+36+(-39)+42+(-45)+48
b)(3^5×27-2^15×2):3^18
c)-2989+[989-(297:3^2+2^2×3^3)]
1,Tính: a) (-53)+36+(-39)+42+(-45)+48 b)(3^5×27-2^15×2):3^18 c)-2989+[989-(297:3^2+2^2×3^3)]
By Maya
By Maya
1,Tính:
a) (-53)+36+(-39)+42+(-45)+48
b)(3^5×27-2^15×2):3^18
c)-2989+[989-(297:3^2+2^2×3^3)]
Đáp án:
$\begin{array}{l}
a)\left( { – 53} \right) + 36 + \left( { – 39} \right) + 42 + \left( { – 45} \right) + 48\\
= \left( { – 53} \right) – 3 – 3 + 48\\
= \left( { – 53} \right) + 48 – 6\\
= – 53 + 42\\
= – \left( {53 – 42} \right)\\
= – 11\\
b)\left( {{3^5}.27 – {2^{15}}.2} \right):{3^{18}}\\
= \left( {{3^5}{{.3}^3} – {2^{16}}} \right):{3^{18}}\\
= {3^8}:{3^{18}} – {2^{16}}:{3^{18}}\\
= \frac{1}{{{3^{10}}}} – \frac{{{2^{16}}}}{{{3^{18}}}}\\
c) – 2989 + \left( { – 989 – \left( {297:{3^2} + {2^2}{{.3}^3}} \right)} \right)\\
= – 2989 + 989 + \left( {297:9 + 4.27} \right)\\
= – 2000 + 33 + 108\\
= – 2000 + 141\\
= – 1859
\end{array}$