a

A. i = 70 độ; r = 70 độ.

Trả lời:

A. i = 70 độ; r = 70 độ.

Chúc bạn học tốt nhé.

nhân là dấu chấm

\(35.60-70.20+35.20\)

= \(35.\left(60+20\right)-70.20\)

= \(35.80-70.20\)

= \(35.4.20-70.20\)

=  \(20.\left(140-70\right)\)

=  \(20.70=1400\)

\(35\times60-70\times20+35\times20\)

\(=35\times30\times20-70\times20+35\times20\)

\(=1005\times20-70\times20+35\times20\)

\(=20\times\left(1005-70+35\right)\)

\(=20\times970\)

\(=19400\)

Giải

35 × 60 - 70 × 20 + 35 × 20

Đổi: 35 × 60 = 105 × 20

=> 105 × 20 - 70 × 20 + 35 × 20

=> 20 × (105 - 70 + 35)

=> 20 × 70

=> 1400

\(\dfrac{4}{7}=\dfrac{8}{14}=\dfrac{12}{21}=\dfrac{16}{28}=\dfrac{20}{35}=\dfrac{40}{70}\)

4/7=8/14=12/21=16/28=20/35=40/70

a)x=39,b)x=-53,c)x=-102,d)x=3,e)x=-61

Chọn B

b

$\frac{1}{20}+\frac{2}{35}+\frac{3}{70}+\frac{4}{140}+\frac{5}{266}+\frac{6}{475}$

$=(\frac{1}{20}+\frac{3}{70}+\frac{4}{140})+(\frac{2}{35}+\frac{5}{266}+\frac{6}{475})$

$=\frac{17}{140}+\frac{31}{350}$

$=\frac{21}{100}$

A = \(\dfrac{1}{20}\) + \(\dfrac{2}{35}\) + \(\dfrac{3}{70}\) + \(\dfrac{4}{140}\) + \(\dfrac{5}{266}\) + \(\dfrac{6}{475}\)

A = \(\dfrac{1}{4\times5}\)+ \(\dfrac{2}{5\times7}\)+ \(\dfrac{3}{7\times10}\)+ \(\dfrac{4}{10\times14}\)+\(\dfrac{5}{14\times19}\)+\(\dfrac{6}{19\times25}\)

A = \(\dfrac{1}{4}\)-\(\dfrac{1}{5}\)+\(\dfrac{1}{5}\)-\(\dfrac{1}{7}\)+\(\dfrac{1}{7}\)-\(\dfrac{1}{10}\)+\(\dfrac{1}{10}\)+\(\dfrac{1}{10}\)-\(\dfrac{1}{14}\)+\(\dfrac{1}{14}\)-\(\dfrac{1}{19}\)+\(\dfrac{1}{19}\)-\(\dfrac{1}{25}\)

A = \(\dfrac{1}{4}\)-\(\dfrac{1}{25}\)

A = \(\dfrac{21}{100}\)

14 . 35 . 5 + 10 . 25 . 7 + 20 . 70

= ( 14 . 5 ) . 35 + ( 10 . 7 ) . 25 + 20 . 70

= 70 . 35 + 70 . 25 + 20 . 70

= 70 . ( 35 + 25 + 20 )

= 70 . 80

= 5600

toán lớp 6 phải thay dấu nhân thành dấu chấm nhé! ;3

14 x 35 x 5 + 10 x 25 x 7 + 20 x 70 = 5600

Chúc bn hok tốt!

585

(15+75)+(20+70)+(25+65)+(30+60)+(35+55)+(40+50)+45
= 90+90+90+90+90+90+45
= 90.6+45
= 540+45=585

Số số hạng là:

(75-15):5+1=13(số)

Tổng là:

45x13=585