[ 212 + ( 48 - 2 . x . x2 ) : 40 - 3 = 3
[ 212 + ( 48 - 2 . x . x2 ) : 40 = 3 + 3 = 6
[ 212 + ( 48 - 2 . x . x2 ) = 6 . 40 = 240
=> 48 - 2 . x . x2 = 240 - 212 = 28
2 . x . x2 = 48 - 28 = 20
x. x2 = 20 : 2 = 10
\(\orbr{\begin{cases}\\\end{cases}}6+\left(\frac{1}{2}\right)^3-\left|-\frac{1}{2}\right|\orbr{\begin{cases}\\\end{cases}\frac{3}{2}}\)
\(\orbr{\begin{cases}\\\end{cases}\left(-25\right)}.\left(-27\right).\left(-x\right)\orbr{\begin{cases}\\\end{cases}}:y\)với a = 5 ; b = -3
\(\left(0,125+40\%-\frac{3}{40}\right)\):\(\orbr{\begin{cases}\\\end{cases}11\frac{3}{7}+8\frac{1}{2}-\left(\frac{13}{12}-5\frac{4}{7}\right)}\)
\(\orbr{\begin{cases}\\4\frac{1}{2}:2,5-40\%+\left(-\frac{1}{5}\right)\end{cases}}.\frac{5}{9}\)
\(2010-2000:\orbr{\begin{cases}\\\end{cases}486}-2\left(49-6\right)\)
Tính hợp lí :\(\orbr{\begin{cases}\\\end{cases}9-\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{10}\right):\left(\frac{1}{2}+\frac{2}{3}+\frac{3}{4}+...+\frac{9}{10}\right)}\)
mk là KHÁNH LINH.
Tính tổng :
\(S_n=\frac{3}{\left(1.2\right)^2}+\frac{5}{\left(2.3\right)^2}+...+\frac{2_n+1}{\orbr{\begin{cases}\\n\left(n+1\right)^2\end{cases}}}\)
phép tính sau đây có kết quả là 144000 hay 160:
\(x:\orbr{\begin{cases}\\\end{cases}\left(1800+600\right):30}=545:\left(315-45\right)\)
a) 4.52-32:24
b) 5871:\(\orbr{\begin{cases}\\\end{cases}}928-\left(247-82.5\right)\)
c) 777:7+1331:113
