Question

Tìm x. a)(9/2-2x)(-11/2)=-11/15.                 b)(x-5/6):9/21=-7/5.                            c)2x+3x=-15

Answer 1

a)\(\left(\frac{9}{2}-2x\right)\left(\frac{-11}{2}\right)=\frac{-11}{15}\)

    \(-\frac{99}{4}-\left(-11x\right)=\frac{-11}{15}\)

    \(-\frac{99}{4}+11x=\frac{-11}{15}\)

    \(11x=\frac{-11}{15}-\left(-\frac{90}{4}\right)\)

     \(11x=\frac{653}{30}\)

      \(x=\frac{653}{30}:11\)

     \(x=\frac{653}{330}\)

Vậy \(x=\frac{653}{330}\)

b)\(\left(x-\frac{5}{6}\right):\frac{9}{21}=-\frac{7}{5}\)

    \(\left(x-\frac{5}{6}\right)=-\frac{7}{5}.\frac{9}{21}\)

      \(x-\frac{5}{6}=-\frac{3}{5}\)

     \(x=\frac{7}{30}\)

Vậy \(x=\frac{7}{30}\)

c)2x+3x=-15

   5x=-15

   x=-15:5

   x=-3

Vậy x=-3