A=\(\dfrac{3^2}{5.14}+\dfrac{3^2}{7.18}+\dfrac{3^2}{9.22}+\dfrac{3^2}{11.26}+\dfrac{3^2}{13.30}\)

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NV

Nguyen Van Thuan

15 tháng 4 2018

A=\(\dfrac{3^2}{5.14}+\dfrac{3^2}{7.18}+\dfrac{3^2}{9.22}+\dfrac{3^2}{11.26}+\dfrac{3^2}{13.30}\)

1

DH

Đồ hút HP ngọc rồng online

15 tháng 4 2018

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Các câu hỏi dưới đây có thể giống với câu hỏi trên

DV

Dung Van

27 tháng 4 2017

A=\(\dfrac{3^2}{5.14}+\dfrac{3^2}{7.18}+\dfrac{3^2}{9.22}+\dfrac{3^2}{11.26}+\dfrac{3^2}{13.30}\)

Không được sử dụng máy tính!!Trình bày ra dùm mình nha

1

MV

Mới vô

27 tháng 4 2017

\(A=\dfrac{3^2}{5\cdot14}+\dfrac{3^2}{7\cdot18}+\dfrac{3^2}{9\cdot22}+\dfrac{3^2}{11\cdot26}+\dfrac{3^2}{13\cdot30}\\ =3^2\cdot\left(\dfrac{1}{5\cdot14}+\dfrac{1}{7\cdot18}+\dfrac{1}{9\cdot22}+\dfrac{1}{11\cdot26}+\dfrac{1}{13\cdot30}\right)\\ =9\cdot\dfrac{1}{2}\cdot\left(\dfrac{1}{5\cdot7}+\dfrac{1}{7\cdot9}+\dfrac{1}{9\cdot11}+\dfrac{1}{11\cdot13}+\dfrac{1}{13\cdot15}\right)\\ =\dfrac{9}{2}\cdot\dfrac{1}{2}\cdot\left(\dfrac{2}{5\cdot7}+\dfrac{2}{7\cdot9}+\dfrac{2}{9\cdot11}+\dfrac{2}{11\cdot13}+\dfrac{2}{13\cdot15}\right)\\ =\dfrac{9}{4}\cdot\left(\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{13}+\dfrac{1}{13}-\dfrac{1}{15}\right)\\ =\dfrac{9}{4}\cdot\left(\dfrac{1}{5}-\dfrac{1}{15}\right)\\ =\dfrac{9}{4}\cdot\dfrac{2}{15}\\ =\dfrac{3}{10}\)

HN

huỳnh ngọc thanh vân

8 tháng 4 2018 - olm

tính: A = \(\frac{3^2}{5.14}+\frac{3^2}{7.18}+\frac{3^2}{9.22}+\frac{3^2}{11.26}+\frac{3^2}{13.30}\)

0

HN

huỳnh ngọc thanh vân

12 tháng 4 2018 - olm

TÍNH A: \(\frac{3^2}{5.14}+\frac{3^2}{7.18}+\frac{3^2}{9.22}+\frac{3^2}{11.26}+\frac{3^2}{13.30}\)

1

AK

Arima Kousei

12 tháng 4 2018

\(\frac{3^2}{5.14}+\frac{3^2}{7.18}+\frac{3^2}{99.22}+\frac{3^2}{11.26}+\frac{3^2}{13.30}\)

\(=\frac{9}{5.14}+\frac{9}{7.18}+\frac{9}{9.22}+\frac{9}{11.26}+\frac{9}{13.30}\)

\(=\frac{9}{2}.\left(\frac{4}{10.14}+\frac{4}{14.18}+\frac{4}{18.22}+\frac{4}{22.26}+\frac{4}{26.30}\right)\)

\(=\frac{9}{2}.\left(\frac{1}{10}-\frac{1}{14}+\frac{1}{14}-\frac{1}{18}+...+\frac{1}{26}-\frac{1}{30}\right)\)

\(=\frac{9}{2}.\left(\frac{1}{10}-\frac{1}{30}\right)\)

\(=\frac{9}{2}.\left(\frac{3}{30}-\frac{1}{30}\right)\)

\(=\frac{9}{2}.\frac{2}{30}\)

\(=\frac{9}{30}\)

\(=\frac{3}{10}\)

Chúc bạn học tốt !!!

DD

ĐINH ĐÔNG QUÝ

3 tháng 6 2019 - olm

A= 3² phần 5.14 + 3² phần 7.18 + 3² phần 9.22 + 3² phần 11.26 + 3² phần 13.30 không sử dụng máy tính nha!!!

2

NL

Nguyễn Linh Chi

3 tháng 6 2019

\(\frac{3^2}{5.14}+\frac{3^2}{7.18}+\frac{3^2}{9.22}+\frac{3^2}{11.26}+\frac{3^2}{13.30}\)

\(=3^2.2.\left(\frac{1}{10.14}+\frac{1}{14.18}+\frac{1}{18.22}+\frac{1}{22.26}+\frac{1}{26.30}\right)\)

\(=9.2.\frac{1}{4}.\left(\frac{14-10}{14.10}+\frac{18-14}{14.18}+\frac{22-18}{18.22}+\frac{26-22}{22.26}+\frac{30-26}{26.30}\right)\)

\(=\frac{9}{2}\left(\frac{1}{10}-\frac{1}{14}+\frac{1}{14}-\frac{1}{18}+\frac{1}{18}-\frac{1}{22}+\frac{1}{22}-\frac{1}{26}+\frac{1}{26}-\frac{1}{30}\right)\)

=\(\frac{9}{2}.\left(\frac{1}{10}-\frac{1}{30}\right)=\frac{9}{2}.\frac{1}{15}=\frac{3}{10}\)

XO

Xyz OLM

3 tháng 6 2019

\(\frac{3^2}{5.14}+\frac{3^2}{7.18}+\frac{3^2}{9.22}+\frac{3^2}{13.30}\)

= \(2.\left(\frac{3^2.}{5.2.14}+\frac{3^2}{2.7.18}+\frac{3^2}{2.9.22}+\frac{3^2}{2.13.30}\right)\)

= \(2.\left(\frac{3^2}{10.14}+\frac{3^2}{14.18}+\frac{3^2}{18.22}+\frac{3^2}{26.30}\right)\)

= \(2.\frac{3^2}{4}\left(\frac{4}{10.14}+\frac{4}{14.18}+\frac{4}{18.22}+\frac{4}{26.30}\right)\)

= \(\frac{9}{2}\left(\frac{1}{10}-\frac{1}{14}+\frac{1}{14}-\frac{1}{18}+\frac{1}{18}-\frac{1}{22}+\frac{1}{195}\right)\)

= \(\frac{9}{2}.\left(\frac{1}{10}-\frac{1}{22}+\frac{1}{195}\right)\)

= \(\frac{9}{2}.\left(\frac{3}{55}+\frac{1}{195}\right)\)

=\(\frac{9}{2}.\frac{128}{2145}\)

= \(\frac{192}{715}\)

MC

Milk Candy

4 tháng 5 2017 - olm

Tính:

A= \(\frac{3^2}{5.14}\)+\(\frac{3^2}{7.18}\)+\(\frac{3^2}{9.22}\)+\(\frac{3^2}{11.26}\)+\(\frac{3^2}{13.30}\).

1

NH

Nguyễn Hoàng Phúc

4 tháng 5 2017

A =\(\frac{3^2}{5.14}+\frac{3^2}{7.18}+\frac{3^2}{9.22}+\frac{3^2}{11.26}+\frac{3^2}{13.30}\)

A =\(3^2.\left(\frac{1}{5.14}+\frac{1}{7.18}+\frac{1}{9.22}+\frac{1}{11.26}+\frac{1}{13.30}\right)\)

A =\(9.\frac{1}{2}.\left(\frac{2}{5.7}+\frac{2}{7.9}+\frac{2}{9.11}+\frac{2}{11.13}+\frac{2}{13.15}\right)\)

A =\(\frac{9}{4}.\left(\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}+\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}\right)\)

A =\(\frac{9}{4}.\left(\frac{1}{5}-\frac{1}{15}\right)\)

A =\(\frac{9}{4}.\frac{2}{15}\)

A =\(\frac{3}{10}\)

GS

G.R senpai

9 tháng 6 2020 - olm

A= \(x = {3^2 \over 3.7}+{3^2 \over 7.9}+{3^2 \over 9.22}+{3^2 \over 11.26}+{3^2 \over 13.30}\)(ko dùng máy tính) giả giùm v heheh)

0

()

5 tháng 4 2018 - olm

Bài 1:1. Rút gọn:a) \(A=\frac{9^3.25^3}{18^2.125^2}\)b) \(B=\frac{18}{37}+\frac{8}{2017}+\frac{19}{37}-1\frac{2009}{2017}+\frac{2017}{2018}\)2.CHO \(M=\frac{2}{5.14}+\frac{2}{7.18}+\frac{2}{9.22}+\frac{2}{11.26}+\frac{2}{13.30}\).so sánh M &\(\frac{3}{46}\)Bài 2:...

1

B

bímậtnhé

5 tháng 4 2018

bài 1.a)\(A=\frac{9^3.25^3}{18^2.125^2}=\frac{3^6.5^6}{2^2.3^4.5^6}=\frac{9}{4}\)

b) \(B=\frac{18}{37}+\frac{19}{37}+\frac{8}{2017}-\frac{4026}{2017}+\frac{2017}{2018}\)

\(=1-\frac{4014}{2017}+\frac{2017}{2018}=\frac{1997}{2017}+\frac{2017}{2018}\)

NP

Nguyễn Phương Anh

13 tháng 4 2023 - olm

Rút gọn các biểu thức sau: a) A = 1 + \(\dfrac{1}{3}\) + \(\dfrac{1}{3^2}\) + \(\dfrac{1}{3^3}\) +...+ \(\dfrac{1}{3^n}\) b) B = \(\dfrac{1}{2}\) - \(\dfrac{1}{2^2}\) + \(\dfrac{1}{2^3}\) - \(\dfrac{1}{2^4}\) +...+ \(\dfrac{1}{2^{99}}\) - \(\dfrac{1}{2^{100}}\) c) C = \(\dfrac{3}{2^2}\) x \(\dfrac{8}{3^2}\) x \(\dfrac{15}{4^2}\) ... \(\dfrac{899}{30^2}\) (Mình cần gấp...

3

NT

Nguyễn Thị Thương Hoài

Giáo viên VIP

14 tháng 4 2023

b, B = \(\dfrac{1}{2}\) - \(\dfrac{1}{2^2}\) + \(\dfrac{1}{2^3}\) - \(\dfrac{1}{2^4}\)+.....+ \(\dfrac{1}{2^{99}}\) - \(\dfrac{1}{2^{100}}\)

2 \(\times\) B = 1 + \(\dfrac{1}{2}\) + \(\dfrac{1}{2^2}\) - \(\dfrac{1}{2^3}\) + \(\dfrac{1}{2^4}\)-.......-\(\dfrac{1}{2^{99}}\)

2 \(\times\) B + B = 1 - \(\dfrac{1}{2^{100}}\)

3B = ( 1 - \(\dfrac{1}{2^{100}}\))

B = ( 1 - \(\dfrac{1}{2^{100}}\)) : 3

NT

Nguyễn Thị Thương Hoài

Giáo viên VIP

14 tháng 4 2023

A = 1 + \(\dfrac{1}{3}\) + \(\dfrac{1}{3^2}\)+ \(\dfrac{1}{3^3}\)+......+ \(\dfrac{1}{3^{n-1}}\) + \(\dfrac{1}{3^n}\)

A\(\times\) 3 = 3 + 1 + \(\dfrac{1}{3}\) + \(\dfrac{1}{3^2}\) + \(\dfrac{1}{3^2}\)+....+ \(\dfrac{1}{3^{n-1}}\)

A \(\times\) 3 - A = 3 - \(\dfrac{1}{3^n}\)

2A = 3 - \(\dfrac{1}{3^n}\)

A = ( 3 - \(\dfrac{1}{3^n}\)) : 2

VG

Vũ Gia Linh

9 tháng 7 2023 - olm

A= 12\(\dfrac{2}{5}\) . (\(\dfrac{-7}{3}\)) - 3\(\dfrac{2}{5}\) . (\(\dfrac{-7}{3}\))

B= (\(\dfrac{2}{3}\))³ : (\(\dfrac{2}{3}\))² + (-1\(\dfrac{1}{2}\)) : 150%

3

ND

Nguyễn Đức Trí

9 tháng 7 2023

\(A=12\dfrac{2}{5}.\left(\dfrac{-7}{3}\right)-3\dfrac{2}{5}.\left(\dfrac{-7}{3}\right)\)

\(A=\dfrac{62}{5}.\left(\dfrac{-7}{3}\right)-\dfrac{17}{5}.\left(\dfrac{-7}{3}\right)\)

\(A=\left(\dfrac{-7}{3}\right).\left(\dfrac{62}{5}-\dfrac{17}{5}\right)\)

\(A=\left(\dfrac{-7}{3}\right).\dfrac{45}{5}\)

\(A=-21\)

\(B=\left(\dfrac{2}{3}\right)^3:\left(\dfrac{2}{3}\right)^2+\left(-1\dfrac{1}{2}\right):150\%\)

\(B=\left(\dfrac{2}{3}\right)^1-\dfrac{3}{2}:1,5\)

\(B=\dfrac{2}{3}-\dfrac{3}{2}:\dfrac{3}{2}\)

\(B=\dfrac{2}{3}-1\)

\(B=-\dfrac{1}{3}\)

GH

Gia Hân

VIP

9 tháng 7 2023

A = \(12\dfrac{2}{5}\) . (\(\dfrac{-7}{3}\)) - \(3\dfrac{2}{5}\) . (\(\dfrac{-7}{3}\))

A = (\(\dfrac{-7}{3}\)) . ( \(12\dfrac{2}{5}\) - \(3\dfrac{2}{5}\) )

A = (\(\dfrac{-7}{3}\)) . ( \(\dfrac{62}{5}\) - \(\dfrac{17}{5}\) )

A = (\(\dfrac{-7}{3}\)) . 9

A = \(\dfrac{-7.9}{3}\)

A = \(\dfrac{-63}{3}\) = -21