Question

BT1: Tính nhanh:

1) 45 . ( 13 + 78 ) + 9 . ( 87 + 22 ) .5

2)  43 . 37 + 93 . 43 + 57 . 61 + 69 . 57

 

Answer 1

1)

\(45\left(13+78\right)+9\left(87+22\right)5\)

\(=45\left(13+78\right)+45\left(87+22\right)\)

\(=45\left(13+78+87+22\right)\)

\(=45\left[\left(87+13\right)+\left(78+22\right)\right]\)

\(=45\left[100+100\right]\)

\(=45.200\)

\(=9000\)

2)

\(43+37+93.43+57.61+69.57\)

\(=43\left(37+93\right)+57.\left(61+69\right)\)

\(=43.130+57.130\)

\(=130\left(43+57\right)\)

\(=130.100\)

=13000