Giải thích các bước giải:

Ta có:

\(\begin{array}{l}
6,\\
a,\\
{4.5^2} - 18:{3^2} = 4.25 - 18:9 = 100 - 2 = 98\\
b,\\
{3^2}.22 - {3^2}.19 = {3^2}.\left( {22 - 19} \right) = {3^2}.3 = {3^3} = 27\\
c,\\
{2^4}.5 - \left[ {131 - {{\left( {13 - 4} \right)}^2}} \right] = 16.5 - \left[ {131 - {9^2}} \right] = 80 - \left( {131 - 81} \right) = 80 - 50 = 30\\
d,\\
100:\left\{ {250:\left[ {450 - \left( {{{4.5}^3} - {2^2}.25} \right)} \right]} \right\}\\
 = 100:\left\{ {250:\left[ {450 - \left( {4.125 - 4.25} \right)} \right]} \right\}\\
 = 100:\left\{ {250:\left[ {450 - 4.\left( {125 - 25} \right)} \right]} \right\}\\
 = 100:\left\{ {250:\left[ {450 - 4.100} \right]} \right\}\\
 = 100:\left\{ {250:\left[ {450 - 400} \right]} \right\}\\
 = 100:\left\{ {250:50} \right\}\\
 = 100:5\\
 = 20\\
e,\\
{2^3}.15 - \left[ {115 - {{\left( {12 - 5} \right)}^2}} \right] = 8.15 - \left[ {115 - {7^2}} \right]\\
 = 120 - \left[ {115 - 49} \right] = 120 - 66 = 54\\
f,\\
30.\left\{ {175:\left[ {355 - \left( {135 + 37.5} \right)} \right]} \right\}\\
 = 30.\left\{ {175:\left[ {355 - \left( {135 + 185} \right)} \right]} \right\}\\
 = 30.\left\{ {175:\left[ {355 - 320} \right]} \right\}\\
 = 30.\left\{ {175:35} \right\}\\
 = 30.5 = 150\\
g,\\
5871:\left[ {928 - \left( {247 - 82} \right).5} \right] + {2175^0}\\
 = 5871:\left[ {928 - 165.5} \right] + 1\\
 = 5871:\left[ {928 - 825} \right] + 1\\
 = 5871:103 + 1\\
 = 57 + 1 = 58\\
7,\\
a,\\
58 + 7x = 100\\
 \Leftrightarrow 7x = 100 - 58\\
 \Leftrightarrow 7x = 42\\
 \Leftrightarrow x = 42:7\\
 \Leftrightarrow x = 6\\
c,\,\,x - 56:4 = 16\\
 \Leftrightarrow x - 14 = 16\\
 \Leftrightarrow x = 16 + 14\\
 \Leftrightarrow x = 30\\
d,\,\,101 + \left( {36 - 4x} \right) = 105\\
 \Leftrightarrow 36 - 4x = 105 - 101\\
 \Leftrightarrow 36 - 4x = 4\\
 \Leftrightarrow 4x = 36 - 4\\
 \Leftrightarrow 4x = 32\\
 \Leftrightarrow x = 32:4\\
 \Leftrightarrow x = 8\\
e,\,\,\left( {x - 12} \right):12 = 12\\
 \Leftrightarrow x - 12 = 12.12\\
 \Leftrightarrow x - 12 = 144\\
 \Leftrightarrow x = 144 + 12\\
 \Leftrightarrow x = 156\\
f,\,\,\left( {3x - {2^4}} \right){.7^3} = {2.7^4}\\
 \Leftrightarrow 3x - {2^4} = {2.7^4}:{7^3}\\
 \Leftrightarrow 3x - 16 = {2.7^{4 - 3}}\\
 \Leftrightarrow 3x - 16 = 2.7\\
 \Leftrightarrow 3x - 16 = 14\\
 \Leftrightarrow 3x = 16 + 14\\
 \Leftrightarrow 3x = 30\\
 \Leftrightarrow x = 30:3\\
 \Leftrightarrow x = 10
\end{array}\) 

Đáp án:

≡.≡ 

Giải thích các bước giải:

\begin{array}{l} 6,\\ a,\\ {4.5^2} - 18:{3^2} = 4.25 - 18:9 = 100 - 2 = 98\\ b,\\ {3^2}.22 - {3^2}.19 = {3^2}.\left( {22 - 19} \right) = {3^2}.3 = {3^3} = 27\\ c,\\ {2^4}.5 - \left[ {131 - {{\left( {13 - 4} \right)}^2}} \right] = 16.5 - \left[ {131 - {9^2}} \right] = 80 - \left( {131 - 81} \right) = 80 - 50 = 30\\ d,\\ 100:\left\{ {250:\left[ {450 - \left( {{{4.5}^3} - {2^2}.25} \right)} \right]} \right\}\\  = 100:\left\{ {250:\left[ {450 - \left( {4.125 - 4.25} \right)} \right]} \right\}\\  = 100:\left\{ {250:\left[ {450 - 4.\left( {125 - 25} \right)} \right]} \right\}\\  = 100:\left\{ {250:\left[ {450 - 4.100} \right]} \right\}\\  = 100:\left\{ {250:\left[ {450 - 400} \right]} \right\}\\  = 100:\left\{ {250:50} \right\}\\  = 100:5\\  = 20\\ e,\\ {2^3}.15 - \left[ {115 - {{\left( {12 - 5} \right)}^2}} \right] = 8.15 - \left[ {115 - {7^2}} \right]\\  = 120 - \left[ {115 - 49} \right] = 120 - 66 = 54\\ f,\\ 30.\left\{ {175:\left[ {355 - \left( {135 + 37.5} \right)} \right]} \right\}\\  = 30.\left\{ {175:\left[ {355 - \left( {135 + 185} \right)} \right]} \right\}\\  = 30.\left\{ {175:\left[ {355 - 320} \right]} \right\}\\  = 30.\left\{ {175:35} \right\}\\  = 30.5 = 150\\ g,\\ 5871:\left[ {928 - \left( {247 - 82} \right).5} \right] + {2175^0}\\  = 5871:\left[ {928 - 165.5} \right] + 1\\  = 5871:\left[ {928 - 825} \right] + 1\\  = 5871:103 + 1\\  = 57 + 1 = 58\\ 7,\\ a,\\ 58 + 7x = 100\\  \Leftrightarrow 7x = 100 - 58\\  \Leftrightarrow 7x = 42\\  \Leftrightarrow x = 42:7\\  \Leftrightarrow x = 6\\ c,\,\,x - 56:4 = 16\\  \Leftrightarrow x - 14 = 16\\  \Leftrightarrow x = 16 + 14\\  \Leftrightarrow x = 30\\ d,\,\,101 + \left( {36 - 4x} \right) = 105\\  \Leftrightarrow 36 - 4x = 105 - 101\\  \Leftrightarrow 36 - 4x = 4\\  \Leftrightarrow 4x = 36 - 4\\  \Leftrightarrow 4x = 32\\  \Leftrightarrow x = 32:4\\  \Leftrightarrow x = 8\\ e,\,\,\left( {x - 12} \right):12 = 12\\  \Leftrightarrow x - 12 = 12.12\\  \Leftrightarrow x - 12 = 144\\  \Leftrightarrow x = 144 + 12\\  \Leftrightarrow x = 156\\ f,\,\,\left( {3x - {2^4}} \right){.7^3} = {2.7^4}\\  \Leftrightarrow 3x - {2^4} = {2.7^4}:{7^3}\\  \Leftrightarrow 3x - 16 = {2.7^{4 - 3}}\\  \Leftrightarrow 3x - 16 = 2.7\\  \Leftrightarrow 3x - 16 = 14\\  \Leftrightarrow 3x = 16 + 14\\  \Leftrightarrow 3x = 30\\  \Leftrightarrow x = 30:3\\  \Leftrightarrow x = 10 \end{array}