a)\(2^{x-1}+5.2^{x-2}=\frac{7}{32}\)

\(\Leftrightarrow2^{x-2}.2+5.2^{x-2}=\frac{7}{32}\)

\(\Leftrightarrow2^{x-2}\left(5+2\right)=\frac{7}{32}\)

\(\Leftrightarrow2^{x-2}.7=\frac{7}{32}\)

\(\Leftrightarrow2^{x-2}=\frac{1}{32}\)

\(\Leftrightarrow2^{x-2}=2^{-5}\)

\(\Leftrightarrow x-2=-5\)

\(\Leftrightarrow x=-3\)

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

\(\Leftrightarrow\left|x+\frac{1}{5}\right|=2\)

\(\Leftrightarrow\orbr{\begin{cases}x+\frac{1}{5}=2\\x+\frac{1}{5}=-2\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=\frac{9}{5}\\x=\frac{-11}{5}\end{cases}}\)

ta có \(\text{2xy + x - 2y = 4}\)

\(\Leftrightarrow\text{2y(x - 1) + x = 4}\)

\(\Leftrightarrow\text{2y(x - 1) + x - 1 = 3}\)

\(\Leftrightarrow\text{2y(x - 1) + (x - 1) = 3}\)

\(\Leftrightarrow\text{(x - 1).(2y + 1) = 3}\)

=> x-1 và 2y+1 thuộc Ư(3)

\(\RightarrowƯ\left(3\right)=\left\{\text{-3;-1;1;3}\right\}\)

vậy các cặp x,y thỏa mãn là ...

b) tương tự

\(\frac{2^{15}.7-2^{16}}{5.2^{15}}=\frac{2^{15}.\left(7-2\right)}{5.2^{15}}=\frac{2^{15}.5}{5.2^{15}}=1\)

Bạn viết lại đề bài đi rồi mình làm cho!!!

ai nhanh k 2 lan

1.

7^6 ÷ 7^4 + 2^3 . 2^2 - 225 ÷ 15^2

= 49 + 32 - 0

= 81.

bạn bấm máy tính đi

Câu a:

(x - 5)^2 - 2x - 2^4 = 2x

(x - 5)(x - 5) - 2x - 16 - 2x = 0

x^2 - 5x - 5x + 25 - 2x - 16 - 2x = 0

x^2 - (5x + 5x +2x + 2x) + (25 - 16) = 0

x^2 - 14x + 9 = 0

(x^2 - 7x) - (7x - 49) - 40 = 0

x(x - 7) - 7(x - 7) - 40 = 0

(x - 7)(x - 7) - 40 = 0

(x - 7)^2 = 40

x - 7 = \(\sqrt{40}\) hoặc x - 7 = -\(\sqrt{40}\)

x - 7 = - \(\sqrt{40}\)

x = 7 - \(\sqrt{40}\)

x - 7 = \(\sqrt{40}\)

x = 7+ \(\sqrt{40}\)

Vậy x ∈ {7 - \(\sqrt{40}\) ; 7+ \(\sqrt{40}\))

Câu b:

3^(x -1) - 7^2 = 2^5 + 0^3

3^(x -1) - 49 = 32 + 0

3^(x - 1) - 49 = 32

3^(x -1) = 32 + 49

3^(x -1) = 81

3^(x-1) = 3^4

x - 1 = 4

x = 4 + 1

x = 5

Vậy x = 5

a. \(\left(\frac{8}{27}\right)^x=\left(\frac{2}{3}\right)^{72}\)

\(\left(\frac{2}{3}\right)^{3x}=\left(\frac{2}{3}\right)^{72}\)

\(\Rightarrow3x=72\Rightarrow x=24\)

Vậy x = 24 

khó quá bn ơi

2b,

các bạn giải nhanh nha mai mk nộp bài nhanh nha