207 x 16 - 207 x 14 - 207 x 2 + 207

= 207 x ( 16 - 14 - 2 + 1 )

= 207 x 1

= 207

_HT_

207 x 16 - 207 x 14 - 207 x 2 + 207

= 207 x 16 - 207 x 14 - 207 x 2 + 207 x 1

= 207 x ( 16 - 14 - 2 + 1 ) 

= 207 x 1 = 207

\(=-18\)

\(6-7-8+9-10+11+12-13+14-15-16+17-18\)

\(=\left(6-7-8+9\right)+\left(-10+11+12-13\right)+\left(14-15-16+17\right)-18\)

\(=0+0+0-18\)

\(=0-18\)

\(=-18\)

1+1000x1000x2000-(9+2+3)=1+2000000000-14

                                        = 2000000001-14

                                         = 1999999987

Mình đưa ra cái này chứ không đưa ra lời giải:

=19_ _ _ _ _ _ _7

xp

a)26+3x26+26+26x2

=26x1+26x3+26x1+26x2

=26x(1+3+1+2)

=26x7=182

ta co :2 x 99=198=99 x 2

8 x 91 = 819 = 39 x 7

     2 x 18 x 5 

= ( 2 x 5 ) x 18 

=    10 x 18

=       180

2 x 18 x 5

=(2 x 5)x 18

=10 x 18

=180

Trả lời:

\(3\times9+18\times2+2\times9+9\)

\(=3\times9+9\times2\times2+2\times9+9\)

\(=3\times9+9\times4+2\times9+9\)

\(=9\times\left(3+4+2+1\right)\)

\(=9\times10\)

\(=90\)

3 x 9+18 x 2 + 2 x 9 + 9=

3 x 9 + 9 x 2 x 2 +2 x 9 + 9 x 1=

(3+2+2+2+1) x 9 =

=90

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 + 14 + 15 + 16 + 17+18 = 171 nhé

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 + 14 + 15 + 16 + 17+18.  = 171