\(\dfrac{1}{2}.2^n+4.2^n=9.5^n\)

\(2^n\left(\dfrac{1}{2}+4\right)=9.5^n\)

\(2^n.\dfrac{9}{2}=9.5^n\)

Bạn xem thử xem có sai đề bài không ạ

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\(\dfrac{1}{2}\) \(\times\) 2ⁿ + 4 \(\times\) 2ⁿ = 9 \(\times\) 5ⁿ

 ⇒      2ⁿ \(\times\) ( \(\dfrac{1}{2}\) + 4) = 9 \(\times\) 5ⁿ

  ⇒    2ⁿ \(\times\) \(\dfrac{9}{2}\) = 9 \(\times\) 5ⁿ

  ⇒  2ⁿ \(\times\) \(\dfrac{1}{2}\) = 9 \(\times\) 5ⁿ

  ⇒      2ⁿ \(\times\) 2^-1 = 5ⁿ

 ⇒     2^n-1 = 5ⁿ

\(\Rightarrow\) \(\left\{{}\begin{matrix}n-1=0\\n=0\end{matrix}\right.\) 

⇒ \(\left\{{}\begin{matrix}n=1\\n=0\end{matrix}\right.\) vì 1 > 0 nên n không tồn tại 

Kết luận n \(\in\) \(\varnothing\) 

Bài 6 :

a) \(\dfrac{625}{5^n}=5\Rightarrow\dfrac{5^4}{5^n}=5\Rightarrow5^{4-n}=5^1\Rightarrow4-n=1\Rightarrow n=3\)

b) \(\dfrac{\left(-3\right)^n}{27}=-9\Rightarrow\dfrac{\left(-3\right)^n}{\left(-3\right)^3}=\left(-3\right)^2\Rightarrow\left(-3\right)^{n-3}=\left(-3\right)^2\Rightarrow n-3=2\Rightarrow n=5\)

c) \(3^n.2^n=36\Rightarrow\left(2.3\right)^n=6^2\Rightarrow\left(6\right)^n=6^2\Rightarrow n=6\)

d) \(25^{2n}:5^n=125^2\Rightarrow\left(5^2\right)^{2n}:5^n=\left(5^3\right)^2\Rightarrow5^{4n}:5^n=5^6\Rightarrow\Rightarrow5^{3n}=5^6\Rightarrow3n=6\Rightarrow n=3\)

Bài 7 :

a) \(3^x+3^{x+2}=9^{17}+27^{12}\)

\(\Rightarrow3^x\left(1+3^2\right)=\left(3^2\right)^{17}+\left(3^3\right)^{12}\)

\(\Rightarrow10.3^x=3^{34}+3^{36}\)

\(\Rightarrow10.3^x=3^{34}\left(1+3^2\right)=10.3^{34}\)

\(\Rightarrow3^x=3^{34}\Rightarrow x=34\)

b) \(5^{x+1}-5^x=100.25^{29}\Rightarrow5^x\left(5-1\right)=4.5^2.\left(5^2\right)^{29}\)

\(\Rightarrow4.5^x=4.25^{2.29+2}=4.5^{60}\)

\(\Rightarrow5^x=5^{60}\Rightarrow x=60\)

c) Bài C bạn xem lại đề

d) \(\dfrac{3}{2.4^x}+\dfrac{5}{3.4^{x+2}}=\dfrac{3}{2.4^8}+\dfrac{5}{3.4^{10}}\)

\(\Rightarrow\dfrac{3}{2.4^x}-\dfrac{3}{2.4^8}+\dfrac{5}{3.4^{x+2}}-\dfrac{5}{3.4^{10}}=0\)

\(\Rightarrow\dfrac{3}{2}\left(\dfrac{1}{4^x}-\dfrac{1}{4^8}\right)+\dfrac{5}{3.4^2}\left(\dfrac{1}{4^x}-\dfrac{1}{4^8}\right)=0\)

\(\Rightarrow\left(\dfrac{1}{4^x}-\dfrac{1}{4^8}\right)\left(\dfrac{3}{2}+\dfrac{5}{3.4^2}\right)=0\)

\(\Rightarrow\dfrac{1}{4^x}-\dfrac{1}{4^8}=0\)

\(\Rightarrow\dfrac{4^8-4^x}{4^{x+8}}=0\Rightarrow4^8-4^x=0\left(4^{x+8}>0\right)\Rightarrow4^x=4^8\Rightarrow x=8\)

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Bạn viết rõ ràng các phân số ra nhé.

A = \(\dfrac{11}{2^3.3^4.5^2}\) = \(\dfrac{11.5}{2^3.3^4.5^3}\) =  \(\dfrac{55}{2^3.3^4.5^3}\)

B = \(\dfrac{29}{2^2.3^4.5^3}\) = \(\dfrac{29.2}{2^3.3^4.5^3}\) = \(\dfrac{58}{2^3.3^4.5^3}\) 

A < B 

1)1/9 x 3^x = 2187:81=27

            3^x=27:1/9=243=3⁵

            =>x=5

\(\frac{1}{9}.3^4.3^x=3^7\)

\(\Leftrightarrow3^x=3^7:\frac{1}{9}:3^4=243\)

\(\Leftrightarrow3^x=3^5\)

\(\Leftrightarrow x=5\)

a, (3x+1)³=-27                    b, (1/2.2^x+4.2^x ) = 9.25

=> ( 3x+1)³=(-3)³                    => [ 2^x.(1/2+4 ) ]=9.25                                c, ( 3x-2)⁵= - 243

=> 3x+1=-3                       => 2^x.9/2 = 225                                           => ( 3x-2)⁵=(-3)⁵

=>3x=-4                            => 2^x        = 225:9/2                                     => 3x-2=-3

=>  x = -4/3                       => 2^x       = 50 (ko có trường hợp nào )         => 3x= -1

                                                                                                            => x=-1/3

:((

câu 1 : điền dấu > , < , = thích hợp

\(a,0>\left(-25\right).\left(-19\right).\left(-1\right)^{2n}\)

\(b,\left(-3\right)^4.\left(-19\right)^2=3^4.19^2.\left(-1\right)^{100}\)

\(c,\left(-2006\right).9\left(-2007\right)>\left(-2008\right).2009\)

câu 2 : sắp xếp các số theo thứ tự tăng dần

- 37 ; 25 ; 0 ; dấu giá trị tuyệt đối nha / -18 / ;  _ (-19 ) ; _ / - 39 / ; _ ( + 151 )

Có : \(-37;25;0;18;19;-39;-151\)

Thứ tự tăng dần : \(-151;-39;-37;25;19;18;0\)

câu 3 tính

\(\text{a ) -8 + 19}=11\)

\(\text{b ) ( -27 ) : ( -3 )}=9\)

c )\(4-\left(-13\right)=17\)

d )\(\text{ - 9 -13 -( -24 ) + 11=13}\)

\(e,323-6\left[3-7.\left(-9\right)\right]=-73\)

\(f,\left(-3\right)^5.\left(-3\right)^3-9\)\(=6552\)

\(g,9-8.16-13.8\)

\(=9-8.\left(16-13\right)\)

\(=9-8.4\)

\(=9-32\)

\(=-23\)

\(h,\left(-3\right)^2+\left\{-54:\left[\left(-2\right)^3+7.|-2|\right].\left(-2\right)^2\right\}\)

\(=9+\left\{-54:\left[\left(-8\right)+7.2\right].4\right\}\)

\(=9+\left\{-54:\left[\left(-8\right)+14\right].4\right\}\)

\(=9+\left\{-54:6.4\right\}\)

\(=9+\left\{-7.4\right\}\)

\(=9+\left(-28\right)\)

\(=-19\)

học tốt

Sửa đề : \(\left(-\frac{4}{3}\right)^n.\left(\frac{16}{9}\right)^2=\left(-\frac{64}{27}\right)^2\)

=> \(\left(-\frac{4}{3}\right)^n.\left[\left(-\frac{4}{3}\right)^2\right]^2=\left[\left(-\frac{4}{3}\right)^3\right]^2\)

=> \(\left(-\frac{4}{3}\right)^n.\left(-\frac{4}{3}\right)^4=\left(-\frac{4}{3}\right)^6\)

=> \(\left(-\frac{4}{3}\right)^n=\left(-\frac{4}{3}\right)^2\)

=> n = 2