1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 

= ( 1 + 9 ) + ( 2 + 8 ) + ( 3 + 7 ) + ( 4 + 6 ) + 5

= 10 + 10 +10 +10 +5

= 20 +10 +10 +5

= 30 + 10 +5

= 40 + 5

= 45 .

1+2+3+4+5+6+7+8+9

=[9+1]+[8+2]+[7+3]+[6+4]+5

= 10+10+10+10+5=45

nho ung ho mk nha

1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9

= 2 x 12 x 30 x 56 x 9 + 3 + 7 + 11 + 15 + 9

= 24 x 1680 x 9 + 10 + 26 + 9

= 40320 x 9 + 36 + 9

= 362880 + 45

= 362925

= 362925

đáp số 362925

k cho mk nha

!!!!!!!!!!!

   1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9

=( 1 + 9 ) + ( 2 + 8 ) + ( 3 + 7 ) +  ( 4 + 6 ) + 5

= 10 x 4 + 5

=     40   + 5

=           45

1+2+3+4+5+6+7+8+9

= (9+1)+(8+2)+(7+3)+(6+4)+5

= 10 + 10 + 10 + 10 + 5

= 40 + 5

= 45

sai đề

28 + 52 =44 -34

80 =10  VÔ LÝ 

VÌ 80>10 NÊN 80 KHÔNG THỂ BẰNG 10

28+34 - 44+52

=(28+52)+(34-44)

=80-10=70

28+34-44+52

=(28+52)+(44-34)

=80+10

=90

     10 x 60 + 10 x 70 - 10 x 30

= ( 10 x 60 ) + ( 10 x 70 ) - ( 10 x 30 )   

=      160      +      170     -    130

=      160      +           140

=                 200

10*(60+70)-30
10*(130-30)
10*100=1000

=24*(7+3)

=24*10

=240

24 * 7 + 24 * 3 = 24 * ( 7 + 3 ) = 24 * 10 = 240 

\(\frac{36x45}{6x5}\)

\(=\frac{6x6x5x9}{6x5}\)

\(=6x9\)

\(=54\)

\(36.45\div6.5\)

\(=36:6.45:5\)

\(=6.9\)

\(=54\)

 10+20+30+40+50+60+70+80+90

=(10+90)+(20+80)+(30+70)+(40+60)+50

=100 + 100 + 100 + 100 + 50

= 100 x 5 + 50

= 500 + 50 =550

= ( 1 0 + 90) + ( 20 + 80)  + ( 30 + 70) + ( 40 + 6 0) + 50

= 100 + 100 + 100 + 100 + 50

= 400 + 50 

= 450