2⁰  + 124 = 5²

10⁰ + 528 = 23²

=> x=0, y=2

giải rõ dc ko ? @@

a) \(2^x+124=5^7\)

\(2^x=78125-124\)

\(2^x=78001\)

b) \(10^x+528=7^2\)

\(10^x=49-528\)

\(10^x=-479\)

Giải:

a) \(\left(-\dfrac{5}{28}+1,75+\dfrac{8}{35}\right):\left(\dfrac{-39}{20}\right)\)

\(=\left(-\dfrac{5}{28}+\dfrac{7}{4}+\dfrac{8}{35}\right):\left(\dfrac{-39}{20}\right)\)

\(=\left(\dfrac{11}{7}+\dfrac{8}{35}\right):\left(-\dfrac{39}{20}\right)\)

\(=\dfrac{9}{5}:\left(-\dfrac{39}{20}\right)\)

\(=\dfrac{9.\left(-20\right)}{5.39}\)

\(=\dfrac{3.\left(-4\right)}{1.13}\)

\(=\dfrac{-12}{13}\)

b) \(6\dfrac{5}{12}:2\dfrac{3}{4}+11\dfrac{1}{4}.\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)

\(=\dfrac{77}{22}:\dfrac{11}{4}+\dfrac{42}{4}.\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)

\(=\dfrac{77}{22}.\dfrac{4}{11}+\dfrac{42}{4}.\left(\dfrac{5}{15}+\dfrac{3}{15}\right)\)

\(=\dfrac{7}{3}+\dfrac{42}{4}.\dfrac{8}{15}\)

\(=\dfrac{7}{3}+\dfrac{14.2}{1.3}\)

\(=\dfrac{7}{3}+\dfrac{28}{3}\)

\(=\dfrac{35}{3}\)

c) \(70,5-528:\dfrac{15}{2}\)

\(=70,5-528.\dfrac{2}{15}\)

\(=70,5-\dfrac{1056}{15}\)

\(=70,5-70,4\)

\(=0,1\)

Đáp án cần chọn là: A

a)  47 – x + 15 = 21 ⇔ 47 – x − 15 = 21 ⇔ 47 − x = 21 + 15 ⇔ 7 − x = 36 ⇔ − x = 47 − 36 ⇔ − x = 11 ⇔ x = − 11.

b)  – 5 – 24 – x = – 11 ⇔ − 5 − 24 + x = − 11 ⇔ − 29 + x = − 11 ⇔ x = − 11 + 29 ⇔ x = 18.

c)  11 + 15 – x = 1 ⇔ 15   − x = 1 − 11 ⇔ 15 − x = − 10 ⇔ 15 + 10 = x ⇔ x = 25.