Bài 9:
\(a.142-\left[50-\left(2^3\cdot10-2^3\cdot5\right)\right]\\ =142-\left[50-2^3\cdot\left(10-5\right)\right]\\ =142-\left(50-2^3\cdot5\right)\\ =142-\left(50-40\right)\\ =142-10\\ =132\\ b.375:\left\{32-\left[4+\left(5\cdot3^2-42\right)\right]\right\}-14\\ =375:\left\{32-\left[4+\left(5\cdot9-42\right)\right]\right\}\\ =375:\left[32-\left(4+3\right)\right]\\ =375:\left(32-7\right)\\ =375:25\\ =15\\ c.\left\{210:\left[16+3\left(6+3\cdot2^2\right)\right]\right\}-3\\ =\left\{210:\left[16+3\left(6+12\right)\right]\right\}-3\\ =\left[210:\left(16+3\cdot18\right)\right]-3\\ =210:70-3\\ =3-3\\ =0\\ d.500-\left\{5\cdot\left[409-\left(2^3\cdot3-21\right)^2\right]-1724\right\}\\ =500-\left\{5\cdot\left[409-\left(8\cdot3-21\right)^2\right]-1724\right\}\\ =500-\left[5\cdot\left(409-3^2\right)-1724\right]\\ =500-\left[5\cdot\left(409-9\right)-1724\right]\\ =500-\left(5\cdot400-1724\right)\\ =500-\left(2000-1724\right)\\ =500-276\\ =224\)
Đáp án bài 9:
\(a. 142 - [50 - (2^3 \cdot 10 - 2^3 \cdot 5)] = 142 - [50 - 2^3 (10 - 5)] = 142 - (50 - 2^3 \cdot 5) = 142 - (50 - 40) = 142 - 10 = 132 \)
\(b. 375 : \{32 - [4 + (5 \cdot 3^2 - 42)]\} - 14 = 375 : \{32 - [4 + (5 \cdot 9 - 42)]\} = 375 : [32 - (4 + 3)] = 375 : (32 - 7) = 375 : 25 = 15 \)
\(c. \{210 : [16 + 3(6 + 3 \cdot 2^2)]\} - 3 = \{210 : [16 + 3(6 + 12)]\} - 3 = [210 : (16 + 3 \cdot 18)] - 3 = 210 : 70 - 3 = 3 - 3 = 0 \)
\(d. 500 - \{5 \cdot [409 - (2^3 \cdot 3 - 21)^2] - 1724\} = 500 - \{5 \cdot [409 - (8 \cdot 3 - 21)^2] - 1724\} = 500 - [5 \cdot (409 - 3^2) - 1724] = 500 - [5 \cdot (409 - 9) - 1724] = 500 - (5 \cdot 400 - 1724) = 500 - (2000 - 1724) = 500 - 276 = 224 \)
