i) \(2345-1000\div\left[19-2\left(21-18\right)^2\right]\)

\(=\)\(2345-1000\div\left[19-2.3^2\right]\)

\(=\)\(2345-1000\div\left[19-2.9\right]\)

\(=\)\(2345-1000\div\left[19-18\right]\)

\(=\)\(2345-1000\div1\)

\(=\)\(2345-1000\)

\(=\)\(1345\)

j) \(128-\left[68+8\left(37-35\right)^2\right]\div4\)

\(=\)\(128-\left[68+8.2^2\right]\div4\)

\(=\)\(128-\left[68+8.4\right]\div4\)

\(=\)\(128-\left[68+32\right]\div4\)

\(=\)\(128-100\div4\)

\(=\)\(128-25\)

\(=\)\(3\)

k) \(568-\left\{5\left[143-\left(4-1\right)^2\right]+10\right\}\div10\)

\(=\)\(568-\left\{5\left[143-3^2\right]+10\right\}\div10\)

\(=\)\(568-\left\{5\left[143-9\right]+10\right\}\div10\)

\(=\)\(568-\left\{5.134+10\right\}\div10\)

\(=\)\(568-\left\{670+10\right\}\div10\)

\(=\)\(568-680\div10\)

\(=\)\(568-68\)

\(=\)\(500\)

a) \(107-\left\{38+\left[7.3^2-24\div6+\left(9-7\right)^3\right]\right\}\div15\)

\(=\)\(107-\left\{38+\left[7.3^2-24\div6+2^3\right]\right\}\div15\)

\(=\)\(107-\left\{38+\left[7.9-4+8\right]\right\}\div15\)

\(=\)\(107-\left\{38+\left[63-4+8\right]\right\}\div15\)

\(=\)\(107-\left\{38+67\right\}\div15\)

\(=\)\(107-105\div15\)

\(=\)\(107-7\)

\(=\)\(7\)

b) \(307-\left[\left(180-160\right)\div2^2+9\right]\div2\)

\(=\)\(307-\left[20\div4+9\right]\div2\)

\(=\)\(307-\left[5+9\right]\div2\)

\(=\)\(307-14\div2\)

\(=\)\(307-7\)

\(=\)\(300\)

c) \(205-\left[1200-\left(4^2-2.3\right)^3\right]\div40\)

\(=\)\(205-\left[1200-\left(16-6\right)^3\right]\div40\)

\(=\)\(205-\left[1200-10^3\right]\div40\)

\(=\)\(205-\left[1200-1000\right]\div40\)

\(=\)\(205-200\div40\)

\(=\)\(205-5\)

\(=\)\(200\)

B nha bạn

.

a) I-9 - xI = 12 + 5

I-9 - xI = 17

\(\Rightarrow\hept{\begin{cases}-9-x=17\\x=-9-17\\x=-26\end{cases}hoac\hept{\begin{cases}-9-x=-17\\x=-9-\left(-17\right)\\x=8\end{cases}}}\)

Vậy\(x\in\left\{-26;8\right\}\)

Chúc bạn học tốt !

b) 11 - (x + 84) = 97

11 - x - 84 = 97

11 - 84 - 97 = x

-170 = x

Vậy x = -170

c) - (x + 84) + 213 = -16

-x - 84 + 213 = -16

-84 + 213 + 16 = x

145 = x

Vậy x = 145

e) -2x - (-17) = 15

-2x + 17 = 15

17 - 15 = 2x

2 = 2x

x = 2 : 2

x = 1

Vậy x = 1

Chúc bạn học tốt !

\(5^{20}:\left(5^{15}.6+5^{15}.19\right)\)

\(=5^{20}:\left(5^{15}\left(6+19\right)\right)\)

\(=5^{20}:\left(5^{15}.25\right)\)

\(=5^{20}:\left(5^{15}.5^2\right)\)

\(=5^{20}:\left(5^{15+2}\right)\)

\(=5^{20}:5^{17}\)

\(=5^{20-17}\)

\(=5^3=125\)

a)  5²⁰ : (5¹⁵.6 + 5¹⁵.19)

= 5²⁰  : [ 5¹⁵ . ( 6 + 19 ) ]

= 5²⁰  : [ 5¹⁵ . 25 ]

=  5²⁰  : [ 5¹⁵ . 5² ]

=  5²⁰  : [ 5^{15 + 2} ]

=  5²⁰  : 5¹⁷

= 5^{20 - 17}

= 5³

^{= 125.}

^{Hok tốt !}

đề đâu bạn

cái dấu [] là dấu đối

a)\(x+12=-23+5\)

\(< =>x+12+23-5=0\)

\(< =>x+30=0\)

\(< =>x=-30\)