450 nha !

= 450

(1+9)+(2+8)+(3+7)+(4+6)+(5+5)+(6+4)+(7+3)+(8+2)+(10+90)+(20+80)+(30+70)+(40+60)+(50+50)+(40+60)+(30+70)+(20+80)                            =10+10+10+10+10+10+10+10+100+100+100+100+100+100+100+100=(10x8)+(100x8)                                                                                       = 80 + 800                                                                                       =880 

Tick vs ah

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + x + 29 = 90

x = 90 - 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 29

x=             16

vậy x = 16

\(1+2+3+4+5+6+7+8+9+x+29=90\)

\(\Rightarrow x=90-\left(1+2+3+4+5+6+7+8+9+29\right)\)

\(\Rightarrow x=90-74\)

\(\Rightarrow x=16\)

Vậy x = 16

_Chúc bạn học tốt_

1 + 2 + 3 + 4 + 5 + 5 + 6 + 7 + 8 +9 + x + 29 = 90

x = 90 - ( 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 29 )

x = 90 - 74

x = 16 

 Vậy x = 16

Xiếc áo thuật đây  , muốn xem thêm thì tick 

bấm máy tính là ra chứ j

Y = 1

tích cho mik 3 cái đi mấy bạn

hãy trả lời nhanh lên nào các bạn

1 + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 10 + 10 + 10 + 80 + 90

= ( 1 + 5 ) + ( 1 + 9 ) + ( 2 + 8 ) + ( 3 + 7 ) + ( 4 + 6 ) + ( 10 + 90 ) + ( 10 + 10 + 80 ) + 10

= 6 + 10 + 10 + 10 +10 + 100 + 100 + 10

= 16 + 10 + 10 + 10 + 100 + 100 + 10

= 26 + 10 + 10 + 100 + 100 + 10

= 36 + 10 + 100 + 100 + 10

= 46 + 100 + 100 + 10

= 146 + 100 + 10

= 246 + 10

= 256

Chúc bạn hok tốt !

kết quả là 256

10=100

10 = 100

thoi chiu

90 : 2  :y = 45

  45     :  y= 45

              y = 1 

a; \(\dfrac{1}{4}\) + \(\dfrac{2}{5}\) + \(\dfrac{6}{8}\) + \(\dfrac{9}{15}\) + \(\dfrac{8}{1}\)

= (\(\dfrac{1}{4}\) + \(\dfrac{6}{8}\)) + (\(\dfrac{2}{5}\) + \(\dfrac{9}{15}\)) + \(\dfrac{8}{1}\)

= (\(\dfrac{1}{4}\) + \(\dfrac{3}{4}\)) + (\(\dfrac{2}{5}\) + \(\dfrac{3}{5}\)) + 8

=  1 + 1 + 8

=  2 + 8

= 10

b; \(\dfrac{1}{2}\) + \(\dfrac{2}{4}\) + \(\dfrac{3}{6}\) + \(\dfrac{4}{8}\) + \(\dfrac{5}{10}\) + \(\dfrac{6}{12}\) + \(\dfrac{7}{14}\) + \(\dfrac{8}{16}\) + \(\dfrac{10}{20}\)

=  \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) x (\(\dfrac{2}{2}\) + \(\dfrac{3}{3}\) + \(\dfrac{4}{4}\) + \(\dfrac{5}{5}\)+ \(\dfrac{6}{6}+\dfrac{7}{7}+\dfrac{8}{8}\) + \(\dfrac{10}{10}\))

= \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) x (1 + 1 +1 + 1+ 1+ 1+ 1 +1)

= \(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) x 1 x 8

= \(\dfrac{1}{2}\) + \(\)\(\dfrac{1}{2}\) x 8

= \(\dfrac{1}{2}\) + 4

= \(\dfrac{9}{2}\) 

c; \(\dfrac{1}{10}\) + \(\dfrac{4}{20}\) + \(\dfrac{9}{30}\)+\(\dfrac{16}{40}+\dfrac{25}{50}+\dfrac{36}{60}+\dfrac{49}{70}+\dfrac{64}{80}+\dfrac{81}{90}\)

= \(\dfrac{1}{10}+\dfrac{2}{10}+\dfrac{3}{10}+\dfrac{4}{10}+\dfrac{5}{10}+\dfrac{6}{10}+\dfrac{7}{10}+\dfrac{8}{10}+\dfrac{9}{10}\)

= \(\dfrac{1+2+3+4+5+6+7+8+9}{10}\)

=  \(\dfrac{\left(1+9\right)+\left(2+8\right)+\left(3+7\right)+\left(4+6\right)+5}{10}\)

= \(\dfrac{10+10+10+10+5}{10}\)

= \(\dfrac{\left(10+10+10+10\right)+5}{10}\)

= \(\dfrac{10\times4+5}{10}\)

= \(\dfrac{45}{10}\)

= \(\dfrac{9}{2}\)