1+7+7^2+7^3+.....+7^49+7^50
Thực hiện phép tính giùm mik với !!!!!!!!!!!!!!!!!!!!
K
Khách
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Những câu hỏi liên quan
16 tháng 3 2020
(-7)2+(-49).[ -15+(-7)4:73 ]+(-1)2014
=49+(-49).[-15+ 7]+1
=49+(-49).(-8)+1
=49+392+1
=441+1
=442
Y
25 tháng 4 2022
\(49,=\dfrac{38}{5}-\left(\dfrac{19}{7}+\dfrac{28}{5}\right)\)
\(=\dfrac{38}{5}-\dfrac{19}{7}-\dfrac{28}{5}\)
\(=\left(\dfrac{38}{5}-\dfrac{28}{5}\right)-\dfrac{19}{7}\)
\(=2-\dfrac{19}{7}=-\dfrac{5}{7}\)
\(50,=\dfrac{25}{81}.\dfrac{15}{22}=\dfrac{125}{594}\)
25 tháng 4 2022
mik xinloi ạ câu 50 mik viết sai đề nên mong bạn giải lại giúp ạ <3
3 tháng 5 2016
a.\(\frac{5}{4}+\frac{3}{7}-\frac{1}{2}=\frac{35+12-14}{28}\)\(=\frac{33}{28}\)
D
19 tháng 1 2022
a/ (x-1)2-(4x+3)(2-x)=x2-2x+1-(8x-4x2+6-3x)
=x2-2x+1-8x+4x2-6+3x=5x2-7x-6
b/ (15x3y2 - 6x2y3) : 3x2y2 = 5x - 2y
c/ \(\dfrac{x+7}{x-7}-\dfrac{x-7}{x+7}+\dfrac{4x^2}{x^2-49}\)=\(\dfrac{\left(x+7\right)^2-\left(x-7\right)^2+4x^2}{\left(x-7\right)\left(x+7\right)}\)=\(\dfrac{x^2+14x+49-\left(x^2-14x+49\right)+4x^2}{\left(x-7\right)\left(x+7\right)}\)=\(\dfrac{28x+4x^2}{\left(x-7\right)\left(x+7\right)}\)=\(\dfrac{4x\left(x+7\right)}{\left(x-7\right)\left(x+7\right)}\)=\(\dfrac{4x}{x-7}\)
6 tháng 1 2022
a: \(=x^2-36-x^2-14x-49+14x=-85\)
b: \(=\dfrac{5x+35+4x-28-5x-7}{\left(x-7\right)\left(x+7\right)}=\dfrac{4x}{x^2-49}\)
6 tháng 1 2022
\(a,\left(x+6\right)\left(x-6\right)-\left(x+7\right)^2+14x=x^2-36-x^2-14x-49+14x=-85\\ b,\dfrac{5}{x-7}+\dfrac{4}{x+7}+\dfrac{5x+7}{49-x^2}=\dfrac{5\left(x+7\right)+4\left(x-7\right)-\left(5x+7\right)}{\left(x-7\right)\left(x+7\right)}=\dfrac{5x+35+4x-28-5x-7}{\left(x-7\right)\left(x+7\right)}=\dfrac{4x}{\left(x-7\right)\left(x+7\right)}\)
11 tháng 2 2018
\(B=\frac{1-\frac{1}{\sqrt{49}}+\frac{1}{49}-\frac{1}{\left(7\sqrt{7}\right)^2}}{\frac{\sqrt{64}}{2}-\frac{4}{7}+\frac{2^2}{7^2}-\frac{4}{343}}\)
\(B=\frac{1-\frac{1}{7}+\frac{1}{49}-\frac{1}{343}}{\frac{8}{2}-\frac{4}{7}+\frac{4}{49}-\frac{4}{343}}\)
\(B=\frac{\frac{343}{343}-\frac{49}{343}+\frac{7}{343}-\frac{1}{343}}{4-\frac{4}{7}+\frac{28}{343}-\frac{4}{343}}\)
\(B=\frac{\frac{300}{343}}{\frac{28}{7}-\frac{4}{7}+\frac{24}{343}}\)
\(B=\frac{\frac{300}{343}}{\frac{24}{7}+\frac{24}{343}}\)
\(B=\frac{\frac{300}{343}}{\frac{1323}{343}+\frac{24}{343}}\)
\(B=\frac{300}{343}:\frac{1347}{343}\)
\(B=\frac{100}{449}\)
M
11 tháng 2 2018
\(A=\frac{2^{12}.3^5-4^6.9^2}{\left(2^2.3\right)^6+8^4.3^5}-\frac{5^{10}.7^3-25^5.49^2}{\left(125.7\right)^3+5^9.14^3}\)
\(A=\frac{2^{12}.3^5-2^{12}.3^6}{2^{12}.3^6+2^{12}.3^5}-\frac{5^{10}.7^3-5^{10}.7^6}{5^9.7^3+5^9.2^3.7^3}\)
\(A=\frac{2^{12}.3^5\left(1-3\right)}{2^{12}.3^5.\left(3+1\right)}-\frac{5^{10}.7^3.\left(1-7^3\right)}{5^9.7^3.\left(1+8\right)}\)
\(A=\frac{-2}{4}-\frac{5.\left(-342\right)}{9}\)
\(A=\frac{-1}{2}+\frac{1710}{9}\)
\(A=\frac{-1}{2}+190\)
\(A=\frac{-1}{2}+\frac{380}{2}\)
\(A=\frac{379}{2}\)
TT
2
Đặt \(A=1+7+7^2+...7^{50}\)
\(7\cdot A=7+7^2+7^3+.....+7^{51}\)
\(7\cdot A-A=\left(7+7^2+7^3+.....+7^{51}\right)-\left(1+7+7^2+....+7^{50}\right)\)
\(A.\left(7-1\right)=\left(7-7\right)+\left(7^2-7^2\right)+.....+\left(7^{50}-7^{50}\right)+7^{51}-1\)
\(A\cdot6=7^{51}-1\Rightarrow A=\frac{7^{51}-1}{6}\)