a) 5.11.18 + 9.31.10 + 4.29.45
= 5.11.9.2 + 9.31.5.2 + 2.2.29.9.5
= 9.5.2.(11 + 31 + 2.29)
= 90.100
= 9000
b) 37.39 + 78.14 + 13.85 + 52.55
= 37.39 + 39.2.14 + 13.17.5 + 13.4.11.5
= 39.(37 + 2.14) + 13.5.(17 + 4.11)
= 39.65 + 65.61
= 65.(39 + 61)
= 65.100
= 6500
a) Ta có: \(5\cdot11\cdot18+9\cdot31\cdot10+4\cdot29\cdot45\)
\(=5\cdot9\left(11\cdot2+31\cdot10+4\cdot29\cdot5\right)\)
\(=5\cdot9\cdot\left(22+310+580\right)\)
\(=45\cdot912=41040\)
b) Ta có: \(37\cdot39+78\cdot14+13\cdot85+52\cdot55\)
\(=39\left(37+2\cdot14\right)+13\cdot\left(85+4\cdot55\right)\)
\(=13\left(3\cdot65+85+4\cdot55\right)\)
\(=13\cdot500=6500\)
a) 5.11.18+9.31.10+4.29.45
=5.18.11+9.10.31+2.45.58
=90.11+90.31+90.58
=90.(11+31+58)
=90.100
=9000
b)37.39+78.14+13.85+52.55
=37.39+39.28+13.85+13.220
=39.(37+28)+13.(85+220)
=39.65+13.305
=13.195+13.305
=13.(195+305)
=13.500
=6500
