Question

        Tìm x biết

a)4^X+5=32⁴⁰b)3^6-3x=81^{3c) 4x+3 - 3.4x+7 = 13. 411}d)5.3^x+6 = 2.3⁵+ 3.3⁵

Answer 1

a. \(4^{x+5}=32^{40}\)

 \(\left(2^2\right)^{x+5}=\left(2^5\right)^{40}\)

\(2^{2x+10}=2^{200}\)

\(2x+10=200\)

2x = 190

x = 95.

b. \(3^{6-3x}=81^3\)

\(3^{6-3x}=\left(3^4\right)^3\)

6 - 3x = 12

3x = 6 - 12

3x = -6

x = -2

c. \(4^{x+3}-3.4^{x+7}=13.4^{11}\)

\(4^{x+3}.1-3.4^{x+3}.4^4=13.4^{11}\)

\(4^{x+3}\left(1-3.4^4\right)=13.4^{11}\)

Bài này sai đề rồi em.

d. \(5.3^{x+6}=2.3^5+3.3^5\)

\(5.3^{x+6}=3^5\left(2+3\right)\)

\(5.3^{x+6}=3^5.5\)

\(3^{x+6}=3^5\)

x + 6 = 5

x = 5 - 6 

x = -1.

Answer 2

a) \(4^{x+5}=32^{40}\)

\(\Rightarrow\left(2^2\right)^{x+5}=\left(2^5\right)^{40}\)

\(\Rightarrow2^{2x+10}=2^{200}\)

\(\Rightarrow2x+10=200\)

\(\Rightarrow2x=200-10=190\)

\(\Rightarrow x=190:2=95\)

b) \(3^{6-3x}=81^3\)

\(\Rightarrow3^{6-3x}=\left(3^4\right)^3\)

\(\Rightarrow3^{6-3x}=3^{12}\)

\(\Rightarrow6-3x=12\)

\(\Rightarrow3x=6-12=-6\)

\(\Rightarrow x=\left(-6\right):3=-2\)

c) \(4^{x+3}-3.4^{x+7}=13.4^{11}\)

Sai đề nha

d) \(5.3^{x+6}=2.3^5+3.3^5\)

\(\Rightarrow5.3^{x+6}=\left(2+3\right).3^5\)

\(\Rightarrow5.3^{x+6}=5.3^5\)

\(\Rightarrow x+6=5\)

\(\Rightarrow x=5-6=-1\)

Chúc em học tốt nhé!

Answer 3

\(a,4^{x+5}=32^{40} \)

\(\Rightarrow\left(2^2\right)^{x+5}=\left(2^5\right)^{40}\)

\(\Rightarrow2^{2.x+5}=2^{200}\)

\(\Rightarrow2x+5=200\)

\(\Rightarrow2x=195\)

\(\Rightarrow x=97,5\)

\(b,3^{6-3x}=81^3\)

\(\Rightarrow3^{6-3x}=3^{12}\)

\(\Rightarrow6-3x=12\)

\(\Rightarrow3x=-6\)

Hai câu còn lại cũng tương tự

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