\(2.3^x+5.3^x.3=153\Leftrightarrow2.3^x+15.3^x=153\)

\(\Leftrightarrow17.3^x=153\Leftrightarrow3^x=9\Leftrightarrow x=2\)

\(\Leftrightarrow2.3^x+5.3.3^x=153\)

\(\Leftrightarrow17.3^x=3^2.17\)

\(\Leftrightarrow3^x=3^2\Rightarrow x=2\)

Bạn xem lại đề

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

Nguyễn Thị Mai:

\(^{\frac{1}{2.3}x+\frac{1}{3.4}x+....+\frac{1}{49.50}x=1}\)

Đặt: \(^{\left(\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{49.50}\right)x=1}\)

\(^{\Leftrightarrow\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{49}-\frac{1}{50}\right)x=1}\)

\(^{\Leftrightarrow\frac{1}{2}+\left(\frac{1}{3}-\frac{1}{3}\right)+\left(\frac{1}{4}-\frac{1}{4}\right)+...+\left(\frac{1}{49}-\frac{1}{49}\right)-\frac{1}{50}x=1}\)

\(^{\Leftrightarrow\left(\frac{1}{2}+0+0+...+0-\frac{1}{50}\right)x=1}\)

\(^{\Leftrightarrow\left(\frac{1}{2}-\frac{1}{50}\right)x=1}\)

\(^{\Leftrightarrow\frac{12}{25}x=1}\)

\(^{\Leftrightarrow x=\frac{25}{12}}\)

Tham khảo nha ~~

\(2.3^{x+1}=10.3^{12}+8.3^{12}\\ VP=\left(10+8\right).3^{12}=18.3^{12}=2.3^2.3^{12}\\ =2.3^{2+12}=2.3^{14}\\ VT=VP\\ \Rightarrow2.3^{x+1}=2.3^{14}\\ \Rightarrow x+1=14\\ Vậy:x=14-1=13\)

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

\(2\cdot3^{x+1}=10\cdot3^{12}+8\cdot3^{12}\\\Rightarrow 2\cdot3^{x+1}=3^{12}\cdot(10+8)\\\Rightarrow 2\cdot3^{x+1}=3^{12}\cdot18\\\Rightarrow 2\cdot3^{x+1}=3^{12}\cdot3^2\cdot2\\\Rightarrow 3^{x+1}=3^{12}\cdot3^2\\\Rightarrow 3^{x+1}=3^{14}\\\Rightarrow x+1=14\\\Rightarrow x=14-1\\\Rightarrow x=13\\Vậy:x=13\)

\(\frac{5.18-10.27+15.36}{10.36-20.54+30.72}\)

\(=\frac{5.18-\left(5.2\right).27+\left(5.3\right).36}{\left(5.2\right).36-\left(5.4\right).54+\left(5.6\right).72}\)

\(=\frac{5.18-5.\left(2.27\right)+5.\left(3.36\right)}{5.\left(2.36\right)-5.\left(4.54\right)+5.\left(6.72\right)}\)

\(=\frac{5.18-5.54+5.108}{5.72-5.216+5.432}\)

\(=\frac{5.\left(18-54+108\right)}{5.\left(72-216+432\right)}\)

\(=\frac{5.\left(-36+108\right)}{5.\left(-144+432\right)}\)

\(=\frac{5.72}{5.288}\)

\(=\frac{5.72}{5..4.72}\)

\(=\frac{1}{4}\)

-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

\(-\frac{1}{2}.3x+\frac{3}{4}=-2,25\)

\(\Rightarrow\frac{1}{2}.(-3).x+\frac{1}{2}.\frac{3}{2}=\frac{9}{4}\)

\(\Rightarrow\frac{1}{2}.\left(-3x+\frac{3}{2}\right)=\frac{9}{4}\)

\(\Rightarrow-3x+\frac{3}{2}=\frac{9}{4}:\frac{1}{2}\)

\(\Rightarrow-3x+\frac{3}{2}=\frac{9}{2}\)

\(\Rightarrow-3x=3\)

\(\Rightarrow x=-1\)

\(2\cdot3^x-1=53\\ \Leftrightarrow2\cdot3^x=54\\ \Leftrightarrow3^x=27\\ \Leftrightarrow x=3\)

\(2\cdot3^x-1=53\\ 2\cdot3^x=54\\ 3^x=27\\ 3^x=3^3=>x=3\)

\(...\Rightarrow2.3^x=54\)

\(\Rightarrow3^x=27\)

\(\Rightarrow3^x=3^3\)

\(\Rightarrow x=3\)

giúp  mik với

rut gọn ak

Ta có:

Chọn đáp án B.

Ta có:

Chọn đáp án B.