Question

Câu 2 Tìm x biết:

nhớ trình bày cách giải nhé

Answer 1

a) \(x+\dfrac{3}{2}=\dfrac{9}{2}\)

\(x=\dfrac{9}{2}-\dfrac{3}{2}\)

\(x=3\)

Vậy x = 3 là giá trị cần tìm

b) \(\dfrac{1}{3}x+\dfrac{3}{4}x-75\%=-5\dfrac{1}{4}\)

\(x\left(\dfrac{1}{3}+\dfrac{3}{4}\right)-\dfrac{75}{100}=\dfrac{-19}{4}\)

\(x\left(\dfrac{4}{12}+\dfrac{9}{12}\right)-\dfrac{3}{4}=\dfrac{-19}{4}\)

\(x.\dfrac{13}{12}-\dfrac{3}{4}=\dfrac{-19}{4}\)

\(x.\dfrac{13}{12}=\dfrac{-19}{4}+\dfrac{3}{4}\)

\(x.\dfrac{13}{12}=-4\)

\(x=-4:\dfrac{13}{12}\)

\(x=-\dfrac{48}{13}\)

Vậy..................................

Answer 2

a) x + \(\dfrac{3}{2}\)= \(\dfrac{9}{2}\)

=> x= \(\dfrac{9}{2}\)- \(\dfrac{3}{2}\)

=> x=3

Vậy x=3

b) \(\dfrac{1}{3}\)x + \(\dfrac{3}{4}\)x - 75%= \(-5\dfrac{1}{4}\)

=> x.(\(\dfrac{1}{3}\)+ \(\dfrac{3}{4}\)) - \(\dfrac{3}{4}\)= \(\dfrac{-21}{4}\)

=> x. \(\dfrac{13}{12}\)- \(\dfrac{3}{4}\)=\(\dfrac{-21}{4}\)

=> x. \(\dfrac{13}{12}\)= \(\dfrac{-21}{4}\)+ \(\dfrac{3}{4}\)

=> x. \(\dfrac{13}{12}\)= \(\dfrac{-9}{2}\)

=> x= \(\dfrac{-9}{2}\): \(\dfrac{13}{12}\)= \(\dfrac{-9}{2}\). \(\dfrac{12}{13}\)

=> x= \(\dfrac{-54}{13}\)

Vậy x= \(\dfrac{-54}{13}\)