\(\dfrac{1}{4}\)+\(\dfrac{1}{28}\)+\(\dfrac{1}{70}\)+\(\dfrac{1}{130}\)+\(\dfrac{1}{208}\)+\(\dfrac{1}{304}\)

= \(\dfrac{1}{1x4}\)+\(\dfrac{1}{4x7}\)+\(\dfrac{1}{7x10}\)+\(\dfrac{1}{10x13}\)+\(\dfrac{1}{13x16}\)+\(\dfrac{1}{16x19}\)

= \(\dfrac{1}{3}\)x(\(\dfrac{3}{1x4}\)+\(\dfrac{3}{4x7}\)+\(\dfrac{3}{7x10}\)+\(\dfrac{3}{10x13}\)+\(\dfrac{3}{13x16}\)+\(\dfrac{3}{16x19}\))

= \(\dfrac{1}{3}\)x(\(\dfrac{4-1}{1x4}\)+\(\dfrac{7-4}{4x7}\)+\(\dfrac{10-7}{7x10}\)+\(\dfrac{13-10}{10x13}\)+\(\dfrac{16-13}{13x16}\)+\(\dfrac{19-16}{16x19}\))

= \(\dfrac{1}{3}\)x(\(\dfrac{4}{1x4}\)-\(\dfrac{1}{1x4}\)+\(\dfrac{7}{4x7}\)-\(\dfrac{4}{4x7}\)+\(\dfrac{10}{7x10}\)-\(\dfrac{7}{7x10}\)+\(\dfrac{13}{10x13}\)-\(\dfrac{10}{10x13}\)+\(\dfrac{16}{13x16}\)- \(\dfrac{13}{13x16}\)+ \(\dfrac{19}{16x19}\)-\(\dfrac{16}{16x19}\))
= \(\dfrac{1}{3}\)x(\(\dfrac{1}{1}\)-\(\dfrac{1}{4}\)+\(\dfrac{1}{4}\)-\(\dfrac{1}{7}\)+\(\dfrac{1}{7}\)-\(\dfrac{1}{10}\)+\(\dfrac{1}{10}\)-\(\dfrac{1}{13}\)+\(\dfrac{1}{13}\)-\(\dfrac{1}{16}\)+\(\dfrac{1}{16}\)-\(\dfrac{1}{19}\))
= \(\dfrac{1}{3}\)x(\(\dfrac{1}{1}\)-\(\dfrac{1}{19}\))
= \(\dfrac{1}{3}\)x\(\dfrac{18}{19}\)
= \(\dfrac{6}{19}\)

36 , 5 x 2 + 36, 5 x 9 - 36,5

= 36,5 x 10

= 365

36,5 : 0,5 + 36,5 ×× 9 -36,5

=36,5.2+36,5×9−36,5=36,5.2+36,5×9−36,5

=36,5×(2+9−1)=36,5×(2+9−1)

=36,5×10=36,5×10

=365

Giải hộ mình nha

Lời giải:
Nếu gấp cạnh của hình đó lên 5 lần thì độ dài cạnh là: $4\times 5=20$ (cm) 

Diện tích toàn phần: $6\times 20\times 20=2400$ (cm³)

ko hiểu đầu bài

Cho biết tổng số bánh bao , số đại hòa thượng , tiểu hòa thượng , hòa thượng

Lời giải:
a. Diện tích gạch cần lát là:
$30\times 25+2\times 30\times 1,8+2\times 25\times 1,8=948$ (m²)

b. 

Thể tích bể: $30\times 25\times 1,8=1350$ (m³)

Bể sẽ đầy sau:

$1350:300=4,5$ (giờ)

1+1