1/2.3x+1/3.4x+....+1/49.50x=1
tìm gioi han \(\lim\limits_{x\rightarrow0}\dfrac{\sqrt{1.2x+1}.\sqrt[3]{2.3x+1}.\sqrt[4]{3.4x+1}...\sqrt[2018]{2017.2018x+1}}{x}\)
Câu này thiếu -1 trên tử rồi :v
Tham khảo câu trả lời của mod Lâm Đọc bị lú rồi :D
1 mũ 2 phần 1.2x 2 mũ2 phần 2.3x 3 mũ3 phần 3.4x bốn mũ 2 phàn 4.5
Khó hiểu quá
Giải các phương trình sau: 3 . 4 x + 1 3 . 9 x + 2 = 6 . 4 x + 1 - 1 2 . 9 x + 1
2.3x + 5.3x + 1 = 153
\(2.3^x+5.3^x.3=153\Leftrightarrow2.3^x+15.3^x=153\)
\(\Leftrightarrow17.3^x=153\Leftrightarrow3^x=9\Leftrightarrow x=2\)
\(\Leftrightarrow2.3^x+5.3.3^x=153\)
\(\Leftrightarrow17.3^x=3^2.17\)
\(\Leftrightarrow3^x=3^2\Rightarrow x=2\)
4.3x+2 − 2.3x+1 = 810
Ta có: \(4.3^{x+2}-2.3^{x+1}=810\)
\(4.3^{x+1}.3-2.3^{x+1}=810\)
\(2.3^{x+1}\left(2.3-1\right)=810\)
\(2.3^{x+1}.5=810\)
\(3^{x+1}=81=3^4\)
x+1=4
x=3
Tổng tất cả các nghiệm thực của phương trình log 6 ( 3 . 4 x + 2 . 9 x ) = x + 1 bằng
A. 4
B. 1
C. 0
D. 3
2.3x+1 = 10. 312 + 8. 312
\(2.3^{x+1}=10.3^{12}+8.3^{12}\\ VP=\left(10+8\right).3^{12}=18.3^{12}=2.3^2.3^{12}\\ =2.3^{2+12}=2.3^{14}\\ VT=VP\\ \Rightarrow2.3^{x+1}=2.3^{14}\\ \Rightarrow x+1=14\\ Vậy:x=14-1=13\)
2.3ˣ⁺¹ = 10.3¹² + 8.3¹²
2.3ˣ⁺¹ = 3¹².(10 + 8)
2.3ˣ⁺¹ = 3¹².18
3ˣ⁺¹ = 3¹².18 : 2
3ˣ⁺¹ = 3¹².9
3ˣ⁺¹ = 3¹².3²
3ˣ⁺¹ = 3¹⁴
x + 1 = 14
x = 14 - 1
x = 13
\(2\cdot3^{x+1}=10\cdot3^{12}+8\cdot3^{12}\\\Rightarrow 2\cdot3^{x+1}=3^{12}\cdot(10+8)\\\Rightarrow 2\cdot3^{x+1}=3^{12}\cdot18\\\Rightarrow 2\cdot3^{x+1}=3^{12}\cdot3^2\cdot2\\\Rightarrow 3^{x+1}=3^{12}\cdot3^2\\\Rightarrow 3^{x+1}=3^{14}\\\Rightarrow x+1=14\\\Rightarrow x=14-1\\\Rightarrow x=13\\Vậy:x=13\)
-1/2.3x+3/4=-2,25
-1/2.3x+3/4=-2.25
-1/2.3x+3/4=9/4
-1/2.3x =9/4-3/4
-1/2.3x =3/2
3x =3/2:-1/2
3x =-3
x =-3:3
x =-1
vậy x=-1
\(-\frac{1}{2}.3x+\frac{3}{4}=-2,25\)
\(\Rightarrow\frac{1}{2}.(-3).x+\frac{1}{2}.\frac{3}{2}=\frac{9}{4}\)
\(\Rightarrow\frac{1}{2}.\left(-3x+\frac{3}{2}\right)=\frac{9}{4}\)
\(\Rightarrow-3x+\frac{3}{2}=\frac{9}{4}:\frac{1}{2}\)
\(\Rightarrow-3x+\frac{3}{2}=\frac{9}{2}\)
\(\Rightarrow-3x=3\)
\(\Rightarrow x=-1\)
2.3x-1=53
cíu nhanh mn ớiii
\(2\cdot3^x-1=53\\ \Leftrightarrow2\cdot3^x=54\\ \Leftrightarrow3^x=27\\ \Leftrightarrow x=3\)
\(2\cdot3^x-1=53\\ 2\cdot3^x=54\\ 3^x=27\\ 3^x=3^3=>x=3\)
\(...\Rightarrow2.3^x=54\)
\(\Rightarrow3^x=27\)
\(\Rightarrow3^x=3^3\)
\(\Rightarrow x=3\)