Bài 2:

a) \(2^n-64=0\)

\(2^n=64\)

\(2^n=2^6\)

\(n=6\)

b) \(5.3^{n-3}-405=0\)

\(5.3^{n-3}=405\)

\(3^{n-3}=405:5\)

\(3^{n-3}=81\)

\(n-3=4\)

\(n=4+3\)

\(n=7\)

c) \(4^n.8=2^{15}\)

\(\left(2^2\right)^n.2^3=2^{15}\)

\(2^{2n}.2^3=2^{15}\)

\(2^{2n+3}=2^{15}\)

\(2n+3=15\)

\(2n=15-3\)

\(2n=12\)

\(n=12:2\)

\(n=6\)

d) \(3.2^{n+1}+2^{n+2}=160\)

\(2^{n+1}.\left(3+2\right)=160\)

\(2^{n+1}.5=160\)

\(2^{n+1}=160:5\)

\(2^{n+1}=32\)

\(2^{n+1}=2^5\)

\(n+1=5\)

\(n=5-1\)

\(n=4\)

Bài 1

a) \(2^{11}.64=2^{11}.2^6=2^{17}\)

Do \(16< 17\Rightarrow2^{16}< 2^{17}\)

Vậy \(2^{16}< 2^{11}.64\)

b) Do \(18>17\Rightarrow9^{18}>9^{17}\)   (1)

\(9^{18}=\left(3^2\right)^{18}=3^{36}\)

Do \(36< 37\Rightarrow3^{36}< 3^{37}\)

\(\Rightarrow9^{18}< 3^{37}\)  (2)

Từ (1) và (2) \(\Rightarrow9^{17}< 3^{37}\)

c) \(2^{333}=\left(2^3\right)^{111}=8^{111}\)

\(3^{222}=\left(3^2\right)^{111}=9^{111}\)

Do \(8< 9\Rightarrow8^{111}< 9^{111}\)

Vậy \(2^{333}< 3^{222}\)

d) \(3^{50}=\left(3^2\right)^{25}=9^{25}\)

Do \(9< 11\Rightarrow9^{25}< 11^{25}\)

Vậy \(3^{50}< 11^{25}\)

e) \(37< 38\Rightarrow3^{37}< 3^{38}\) (1)

Lại có: \(3^{38}=3^{2.19}=\left(3^2\right)^{19}=9^{19}\)

Do \(9< 10\Rightarrow9^{19}< 10^{19}\)

\(\Rightarrow3^{38}< 10^{19}\) (2)

Từ (1) và (2) \(\Rightarrow3^{37}< 10^{19}\)

f) Do \(17>16\Rightarrow17^{14}>16^{14}\)   (1)

Do \(32>31\Rightarrow32^{11}>31^{11}\)   (2)

Lại có:

\(16^{14}=\left(2^4\right)^{14}=2^{56}\)

\(32^{11}=\left(2^5\right)^{11}=2^{55}\)

Do \(56>55\Rightarrow2^{56}>2^{55}\)

\(\Rightarrow16^{14}>32^{11}\)   (3)

Từ (1), (2) và (3) \(\Rightarrow17^{14}>31^{11}\)

Mình mắc câu này 

đâu

3: \(\left(3x+5\right)\left(2x-7\right)\)

\(=6x^2-21x+10x-35\)

\(=6x^2-11x-35\)

4: \(\left(5x-2\right)\left(3x+4\right)\)

\(=15x^2+20x-6x-8\)

\(=15x^2+14x-8\)

1.C

2.C

1.C

2.C

tick đúng nhé bn

1.C

1.C

giúp e vs ạ

\(\left(-5\right)^2.\left(-2\right)-\left[\left(-93\right)+\left(8-11\right)^3\right]\\ =25.\left(-2\right)-\left[-93+\left(-3\right)^3\right]\\ =-50-\left(-93-27\right)\\ =-50+93+27\\ =70\)

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