=5x(2+4+6+8)
=5x20
=100

nguyễn thị yến vy            

2x5+4x5+6x5+8x5

= 10 + 20 + 30 + 40

= 100

2*5+4*5+6*5+8*5

= (2+4+6+8)*5

=[(2+8)+(4+6)]*5

=(10+10)*5

=20*5

=100

=1+1/3-1/4+1/4-1/5+1/5-1/6

=4/3-1/6

=8/6-1/6=7/6

Logic qué

=7/6

\(9,65\times0,4\times0,25\)

\(=\)\(9,65\times\left(0,4\times0,25\right)\)

\(=\)\(9,65\times0,1\)

\(=\)\(0,965\)

\(0,25\times40\times9,84\)

\(=\)\(\left(0,25\times40\right)\times9,84\)

\(=\)\(10\times9,84\)

\(=\)\(98,4\)

(9+1)+(8+2)+(7+3)+(6+4)+10+5

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

9+3+2+1+7+8+5+10+6+4= (9+1)+(2+8)+(3+7)+(4+6)+5=10+10+10+10+5=10.4+5=40+5=45

(9+1)+(3+7)+(2+8)+(6+4)+10

=10+10+10+10+10

=50

   86,72 + 9,8 - 12,73 +10,2 - 7,27

= 86,72 - (9,8 + 10,2) - (12,73 + 7,27)

= 86,72 -         20       -             20

= 86,72 -             (20  -  20)

= 86,72 -                  0 

=          86,72.

chúc bạn học tốt nhé!

25x9x4x100:1000

=(25x4)x9x100:1000

=100x9x100:1000

=10000:1000x9

=10x9

=90

\(\frac{2}{3}\times\frac{4}{5}+\frac{4}{5}\times\frac{1}{2}+\frac{4}{5}\times\frac{1}{6}\)

\(=\left(\frac{2}{3}+\frac{1}{2}+\frac{1}{6}\right)\times\frac{4}{5}\)

\(=\frac{4}{3}\times\frac{4}{5}\)

\(=\frac{16}{15}\)