2x+2x+1+2x+2+2x+3+...+2x+2021=22025-8
2x + 2x+1 + 2x+2 +......+2x+2021 =22026 -16
đặt A=2^x +2^x+1 +.....+2^x+2021=2^x+2026-16
đặt 2A = 2^x+1 +2^x+2 +......+2^x+2022=2^x+2027-32
lấy 2A-A =2^x+2022-2^x=2^2026-16
vậy,ta suy ra x=4
2x + 2x+1 + 2x+2 +......+2x+2021 =22026 -16
=>\(2^x\left(1+2+2^2+...+2^{2021}\right)=2^4\left(2^{2022}-1\right)\)
=>2^x=2^4
=>x=4
2x + 2x+1+ 2x+2 + .... + 2x+2021 = 22026 - 16
Đặt \(A=2^x+2^{x+1}+...+2^{x+2021}=2^{x+2026-16}\)
Đặt \(2A=2^{x+1}+2^{x+2}+...+2^{x+2022}=2^{x+2027+32}\)
Ta lấy \(2A-A=2^{x+2022}-2^x=2^{2026-16}\)
\(\Rightarrow x=4\)
Vậy \(x=4\)
\(2VT=2^{x+1}+2^{x+2}+2^{x+3}+...+2^{x+2022}\)
\(VT=2VT-VT=2^{x+2022}-2^x\)
\(\Rightarrow2^{x+2022}-2^x=2^{2026}-16\)
\(\Leftrightarrow2^{2022}.2^x-2^x=2^{2026}-2^4\)
\(\Leftrightarrow2^x\left(2^{2022}-1\right)=2^4\left(2^{2022}-1\right)\)
\(\Leftrightarrow2^x=2^4\Rightarrow x=4\)
\(2^x+2^{x+1}+2^{x+2}+...+2^{x+2021}=2^{2026}-16\)
\(\Rightarrow2^x\left(1+2^x+2^{x+1}+...+2^{x+2020}\right)=2^{2026}-2^4\)
\(\Rightarrow2^x.\dfrac{2^{x+2020+1}-1}{2-1}=2^4.\left(2^{2022}-1\right)\)
\(\Rightarrow2^x.\left(2^{x+2021}-1\right)=2^4.\left(2^{2022}-1\right)\)
\(\Rightarrow x\in\varnothing\)
Tìm x biết
a/ x + 2006 = 2021
b/ 2x - 2016 = 2⁴.4
C/ 3. ( 2x + 1) ³ =81
a) x + 2006 = 2021
x= 2021 - 2006
x= 15
b) 2x - 2016 = 2 4 . 4
2x - 2016 = 64
2x = 64 + 2016
2x = 2080
x= 2080 : 2
x= 1040
c) 3. ( 2x + 1) ³ =81
( 2x-1)3 = 27
( 2x-1)3 = 33
=> 2x-1 = 3
2x= 2
x= 1
a, \(x\) + 2006 = 2021
\(x\) = 2021 - 2006
\(x\) = 15
b, 2\(x\) - 2016 = 24.4
2\(x\) - 2016 = 64
2\(x\) = 64 + 2016
2\(x\) = 2080
\(x\) = 2080 : 2
\(x\) = 1040
Bài 2. (2điểm)Tìm x biếta) 3(2x –3) + 2(2 –x) = –3;b) (x –2021)(x –5) = x –2021;c) (2x –3)2–36x2= 0.
\(a,\Leftrightarrow6x-9+4-2x=-3\Leftrightarrow4x=2\Leftrightarrow x=\dfrac{1}{2}\\ b,\Leftrightarrow\left(x-2021\right)\left(x-6\right)=0\Leftrightarrow\left[{}\begin{matrix}x=2021\\x=6\end{matrix}\right.\\ c,\Leftrightarrow\left(2x-3-6x\right)\left(2x-3+6x\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}-3-4x=0\\8x-3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{3}{4}\\x=\dfrac{3}{8}\end{matrix}\right.\)
Cho các số thực dương x, y, z thỏa mãn 2x + 3y + 4z = 2016
CMR: \(\frac{3y+4z+2021}{1+2x}+\frac{2x+4z+2021}{1+3y}+\frac{2x+3y+2021}{1+4z}\ge15\)
Đặt biểu thức ở vế trái là A.
Ta có: \(A+3=\frac{2x+3y+4z+2022}{1+2x}+\frac{2x+3y+4z+2022}{1+3y}+\frac{2x+3y+4z+2022}{1+4z}=\frac{4038}{1+2x}+\frac{4038}{1+3y}+\frac{4038}{1+4z}\ge4038.\frac{9}{3+2x+3y+4z}=4038.\frac{9}{2019}=18\)
Dấu "=" xảy ra khi và chỉ khi 2x = 3y = 4z = 672
Tính \(lim_{x\rightarrow1}\dfrac{\sqrt{2x+7}-3}{x^3-2x^2+2022x-2021}\)
1)(-1/2)^2:-1/4-2x(-1/2)^3+căn bậc 25-16
2)25^10x(1/5)^20+(-3/8)^8x(-4/3)^8-2021^0
1: \(=\dfrac{1}{4}:\dfrac{-1}{4}-2\cdot\dfrac{-1}{8}+5-4\)
\(=-1+1+\dfrac{1}{4}=\dfrac{1}{4}\)
2: \(=5^{20}\cdot\dfrac{1}{5^{20}}+\left(\dfrac{3}{8}\cdot\dfrac{4}{3}\right)^8-1=1-1+\dfrac{1}{2}^8=\dfrac{1}{2^8}\)
cho đt:p=3a^2x^2+4b^2x^2-2a^2x^2-3b^2x^2+2021;tìm GTNN của p biết a,b khác 0