Bài 16:
a: \(8\cdot5^2-189:3^2\)
\(=8\cdot25-189:9\)
=200-21=179
b: \(200:\left[117-\left(23-6\right)\right]\)
\(=\dfrac{200}{117-17}\)
\(=\dfrac{200}{100}=2\)
c: \(2020-\left[45-\left(6-1\right)^2\right]+2019^0\)
\(=2020-\left[45-5^2\right]+1\)
=2020-20+1
=2001
d: \(476-\left\{5\cdot\left[409-\left(8\cdot3-21^2\right)\right]-1724\right\}\)
\(=476-\left\{5\cdot\left(409-24+441\right)-1724\right\}\)
\(=476-5\cdot826+1724\)
\(=2200-4130=-1930\)
Bài 17:
a: \(287+121+513+79\)
\(=287+513+121+79\)
=800+200=1000
b: \(43\cdot27+93\cdot43+57\cdot61+59\cdot57\)
\(=43\left(27+93\right)+57\left(61+59\right)\)
\(=120\cdot43+120\cdot57=120\cdot100=12000\)
c: \(64\cdot6+81\cdot4+17\cdot6\)
\(=6\left(64+17\right)+81\cdot4\)
\(=81\cdot6+81\cdot4=81\left(6+4\right)=81\cdot10=810\)
d: \(31\cdot65+31\cdot35-600\)
\(=31\left(65+35\right)-600\)
=3100-600=2500
Bài 16:
\(a,8.5^2-189:3^2\)
\(=8.25-189:9\)
\(=200-21\)
\(=179\)
\(b,200:\left[117-\left(23-6\right)\right]\)
\(=200:\left[117-17\right]\)
\(=200:100\)
\(=2\)
\(c,2020-\left[45-\left(6-1\right)^2\right]+2019^0\)
\(=2020-\left[45-5^2\right]+1\)
\(=2020-\left[45-25\right]+1\)
\(=2020-20+1\)
\(=2000+1\)
\(=2001\)
\(d,476-\left\{5.\left[409-\left(8.3-21^2\right)\right]-1724\right\}\)
\(=476-\left\{5.\left[409-\left(-417\right)\right]-1724\right\}\)
\(=476-\left\{5.826-1724\right\}\)
\(=476-\left\{4130-1724\right\}\)
\(=476-2406\)
\(=-1930\)
