7 x 24 x 28 - 49 x 19 - 21 x 35
= 7 x 24 x 28 - 7 x 7 x 19 - 21 x 7 x 5
= 7 x ( 24 x 28 - 7 x 19 - 21 x 5 )
= 7 x 434
= 3038
Ta có:
\(7.24.28-49.19-21.35\)
\(=7.24.4.7-7.7.19-3.7.5.7\)
\(=7.7\left(24.4-19-3.5\right)\)
\(=49\left(96-19-15\right)\)
\(=49.62=3038\)