Tìm x: 5x + 17 = x - 47
Tính nhanh: (12015 - 1012015) x (22015 - 1002015) x (32015 - 992015) x ... x (1012015 - 12015)
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
\(3^{x+3}\cdot2=5^3+37\cdot1^{2015}\\\Rightarrow3^{x+3}\cdot2=125+37\\\Rightarrow3^{x+3}\cdot2=162\\\Rightarrow3^{x+3}=162:2\\\Rightarrow3^{x+3}=81\\\Rightarrow3^{x+3}=3^4\\\Rightarrow x+3=4\\\Rightarrow x=4-3\\\Rightarrow x=1\)
\(3^{x+3}.2=5^3+37.1^{2015}\\ 3^{x+3}.2=125+37.1=125+37=162\\ 3^{x+3}=\dfrac{162}{2}=81=3^4\\ Nên:x+3=4\\ Vậy:x=4-3=1\)
\(A=\frac{1}{3\cdot5}+\frac{1}{5\cdot7}+...+\frac{1}{55\cdot57}\)
\(2A=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{55}-\frac{1}{57}\)
\(2A=\frac{1}{3}-\frac{1}{57}\)
\(2A=\frac{6}{19}\)
\(A=\frac{3}{19}\)
Ta có:
A=1/15+1/35+1/63+1/99+...+1/2015+1/3135
=1/3.5+1/5.7+1/7.9+1/9.11+...+1/45.47+1/47.49
=1/3-1/5+1/5-1/7+1/7-1/9+...+1/45-1/47+1/47-1/49
=1/3-1/49
=49/147-3/147
=47/147
\(2^{x+1}\cdot2^{2014}=2^{2015}\\ 2^{x+1}=2^{2015}:2^{2014}\\ 2^{x+1}=2\\ =>x+1=1\\ x=1-1\\ x=0\)
5x + 17 = x - 47
5x - x = -47 - 17
4x = -64
x = -64 : 4
x = -16
5x+17=x-47
5x-x=-47-17
4x=-64
x=-16