Question

1.tính giá trị biểu thức sau ,tính hợp lí nếu có thể

a) 100 : 5 mũ 2 + 7 x 2 mũ 3     b) 2 mũ 3 x 15 -[149 -(12 - 5)mũ 2 ]

Answer 1

\(a,\)\(100:5^2+7\cdot2^3\)
\(=100:25+7\cdot8\)
\(=4+56\)
\(=60\)
\(b,\)\(2^3\cdot15-\left[149-\left(12-5\right)^2\right]\)
\(=8\cdot15-\left[149-7^2\right]\)
\(=120-\left[149-49\right]\)
\(=120-100\)
\(=20\)

Answer 2

\(100\div5^2+7.2^3\)

\(\Rightarrow5^2.4\div5^2+7.8\)

\(\Rightarrow4+56\)

\(\Rightarrow60\)

Answer 3

$a,$$100:{}^{}+7\cdot {}^{}$
$=100:25+7\cdot 8$
$=4+56$
$=60$
$b,$${}^{}\cdot 15-\left[149-{}^{}\right]$
$=8\cdot 15-\left[149-{}^{}\right]$
$=120-\left[149-49\right]$
$=120-100$
$=20$