a) \(3^{7x-1}=815\)

\(\Leftrightarrow3^{7x}:3=815\)

\(\Leftrightarrow\left(3^7\right)^x:3=815\)

\(\Leftrightarrow2187^x=815.3\)

\(\Leftrightarrow2187^x=2445\)

\(\Rightarrow\) Không có x thoả mãn.

b) \(\left(-0,6\right)^5.x=\left(\dfrac{-3}{5}\right)^8\)

\(\Leftrightarrow x=\left(\dfrac{-3}{5}\right)^8:\left(-0,6\right)^5\)

\(\Leftrightarrow x=\left(-0,6\right)^8:\left(-0,6\right)^5\)

\(\Leftrightarrow x=\left(-0,6\right)^3\)

c) \(\left(0,5-x\right)^3=-8\)

\(\Leftrightarrow\left(0,5-x\right)^3=\left(-2\right)^3\)

\(\Rightarrow0,5-x=-2\)

\(\Leftrightarrow x=0,5+2\)

\(\Leftrightarrow x=2,5\).

Câu b hình như bạn làm sai rồi đó !

a) \(\frac{5}{6}\)x - \(\frac{3}{8}\)x - 10 = 12

=> \(\left(\frac{5}{6}-\frac{3}{8}\right)\)x = 12 + 10

=> \(\frac{11}{24}\)x = 22

=> x = 22 : \(\frac{11}{24}\)

=> x = 48

Vậy x = 48.

b) (\(\left|x\right|\) - \(\frac{1}{8}\)) . \(\left(-\frac{1}{8}\right)^5\) = \(\left(-\frac{1}{8}\right)^7\)

=> \(\left|x\right|\) - \(\frac{1}{8}\) = \(\left(-\frac{1}{8}\right)^7\) : \(\left(-\frac{1}{8}\right)^5\)

=> \(\left|x\right|\) - \(\frac{1}{8}\) = \(\left(-\frac{1}{8}\right)^{7-5}\)

=> \(\left|x\right|\) - \(\frac{1}{8}\) = \(\frac{1}{64}\)

=> \(\left|x\right|\) = \(\frac{1}{64}\) + \(\frac{1}{8}\)

=> \(\left|x\right|\) = \(\frac{9}{64}\)

=> x = \(\frac{9}{64}\) hoặc x = \(\frac{-9}{64}\)

Vậy x = \(\frac{9}{64}\) hoặc x = \(\frac{-9}{64}\)

hên quá làm đúng hì hì, cảm ơn nhen, hết sợ bị sai ồi

a: |x-1/2|=7/2

=>x-1/2=7/2 hoặc x-1/2=-7/2

=>x=4 hoặc x=-3

b: \(x:\dfrac{3}{8}+\dfrac{5}{8}=x\)

=>8/3x-x=-5/8

=>5/3x=-5/8

hay x=-5/8:5/3=-5/8x3/5=-15/40=-3/8

c: \(\dfrac{5}{6}-\left|x-\dfrac{1}{2}\right|=\dfrac{15}{18}=\dfrac{5}{6}\)

=>|x-1/2|=0

=>x-1/2=0

hay x=1/2

e: \(\left(5x-3\right)^2-\dfrac{1}{64}=0\)

=>(5x-3)²=1/64

=>5x-3=1/8 hoặc 5x-3=-1/8

=>5x=25/8 hoặc 5x=23/8

=>x=5/8 hoặc x=23/40

x=9

# yêuToán

a: \(\dfrac{5^5}{5^x}=5^{18}\)

=>5-x=18

hay x=-13

b: \(\dfrac{2^{4-x}}{16^5}=32^6\)

\(\Leftrightarrow2^{4-x}=\left(2^5\right)^6\cdot\left(2^4\right)^5=2^{30+20}=2^{50}\)

=>4-x=50

hay x=-46

c: \(\dfrac{2^{2x-3}}{4^{10}}=8^3\cdot16^5\)

\(\Leftrightarrow2^{2x-3}=2^9\cdot2^{20}\cdot2^{20}=2^{49}\)

=>2x-3=49

=>2x=52

hay x=26

d: \(\dfrac{2^3}{2^x}=4^5\)

\(\Leftrightarrow2^{3-x}=2^{10}\)

=>3-x=10

hay x=-7

e: \(9\cdot5^x=6\cdot5^6+3\cdot5^6\)

\(\Leftrightarrow9\cdot5^x=9\cdot5^6\)

\(\Leftrightarrow5^x=5^6\)

hay x=6

f: \(7\cdot2^x=2^9+5\cdot2^8\)

\(\Leftrightarrow2^x\cdot7=2^8\cdot7\)

\(\Leftrightarrow2^x=2^8\)

hay x=8

a: \(\Leftrightarrow4^x\left(\dfrac{3}{2}+\dfrac{5}{3}\cdot4^2\right)=4^8\left(\dfrac{3}{2}+\dfrac{5}{3}\cdot4^2\right)\)

=>4^x=4^8

=>x=8

b: \(\Leftrightarrow2^x\cdot\dfrac{1}{2}+2^x\cdot2=2^{10}\left(2^2+1\right)\)

=>2^x=2^11

=>x=11

c: =>1/6*6^x+6^x*36=6^15(1+6^3)

=>6^x=6*6^15

=>x=16

d: \(\Leftrightarrow8^x\left(\dfrac{5}{3}\cdot8^2-\dfrac{3}{5}\right)=8^9\left(\dfrac{5}{3}\cdot8^2-\dfrac{3}{5}\right)\)

=>x=9

2, \(\Rightarrow\left\{{}\begin{matrix}\\\dfrac{5}{4}x-\dfrac{7}{2}=0\\\dfrac{5}{8}x+\dfrac{3}{5}=0\\\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}x=\dfrac{14}{5}\\\\x=\dfrac{-24}{25}\\\end{matrix}\right.\)

Bài làm:

\(M=\left(12x^8+8x^2+6x-7\right)-\left(12x^8+2x-8\right)+\left(5-8x^2\right)\)

\(M=4x+6\)

\(M=4x+6\)

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