k. \(\dfrac{3}{2}x-\dfrac{2}{5}=\dfrac{1}{3}x-\dfrac{1}{4}\)

<=> \(\dfrac{3}{2}x-\dfrac{1}{3}x=\dfrac{2}{5}-\dfrac{1}{4}\)

<=> \(\dfrac{7}{6}x=\dfrac{3}{20}\)

<=> \(\dfrac{3}{\dfrac{\dfrac{20}{7}}{6}}=\dfrac{1}{128}\)

:)

Lỗi đấy

:))

a. \(\left(3b+\dfrac{5a}{6}\right)^2\)

= \(9b^2+15ab+\dfrac{25a^2}{36}\)

b. (5x - y)²

= 25x² - 10xy + y²

c. (2a + b - 5)(2a - b + 5)

= 4a² - (b - 5)²

d. \(\left(x^2+\dfrac{2}{5y}\right)\left(x^2-\dfrac{2}{5y}\right)\)

= \(x^4-\dfrac{4}{25y^2}\)

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