Question

Tìm x biết :

a) -2×(x-1/3)-5× (x+1/3)=1/2×x

b) -(1/2×x-3/4)-(-x+1)=-3/2

Cảm ơn nhiều nha!

Answer 1

a) \(-2\left(x-\dfrac{1}{3}\right)-5\left(x+\dfrac{1}{3}\right)=\dfrac{1}{2}x\)

\(\Leftrightarrow-2x+\dfrac{2}{3}-5x-\dfrac{5}{3}=\dfrac{1}{2}x\)

\(\Leftrightarrow-7x-1=\dfrac{1}{2}x\)

\(\Leftrightarrow-7x-\dfrac{1}{2}x=1\)

\(\Leftrightarrow-\dfrac{15}{2}x=1\)

\(\Leftrightarrow x=1:\left(-\dfrac{15}{2}\right)=-\dfrac{2}{15}\)

b) \(-\left(\dfrac{1}{2}x-\dfrac{3}{4}\right)-\left(-x+1\right)=\dfrac{3}{2}\)

\(\Leftrightarrow-\dfrac{1}{2}x+\dfrac{3}{4}+x-1=\dfrac{3}{2}\)

\(\Leftrightarrow\dfrac{1}{2}x-\dfrac{1}{4}=\dfrac{3}{2}\)

\(\Leftrightarrow\dfrac{1}{2}x=\dfrac{3}{2}+\dfrac{1}{4}=\dfrac{7}{4}\)

\(\Leftrightarrow x=\dfrac{7}{4}:\dfrac{1}{2}\)

\(\Leftrightarrow x=\dfrac{7}{2}\)