Question

Tìm x , biết

a) \(\left|x-4\right|=6\)

b) \(\dfrac{x}{5}=\dfrac{9}{7}\)

c) \(1\dfrac{2}{5}x+\dfrac{3}{7}=\dfrac{-4}{5}\)

d) \(\left|x+\dfrac{2}{3}\right|+2=2\dfrac{1}{3}\)

Answer 1

a) |x - 4| = 6

\(\Rightarrow\) \(\pm\)x = \(\pm\)10

\(\Rightarrow\) x = {10, -10}

Answer 2

b) \(\dfrac{x}{5}=\dfrac{9}{7}\)

\(\Rightarrow7x=45\)

\(\Rightarrow x=\dfrac{45}{7}\)

Answer 3

a)\(\left|x-4\right|=6\)

TH1 x-4=6

=> x=6+4

=>x=10

Th2 x-4=-6

=> x=-6+4

=>x=-2

vậy x=10 hoặc x=-2

Answer 4

\(a,\left|x-4\right|=6\)

TH1:\(x-4=6\)

\(x=6+4\)

\(x=10\)

TH2:\(x-4=-6\)

\(x=\left(-6\right)+4\)

\(x=-2\)

Vậy x=10 hoặc x=-2

\(b,\dfrac{x}{5}=\dfrac{9}{7}\)

\(x.7=9.5\)

\(x.7=45\)

\(x=45:7\)

\(x=\dfrac{45}{7}\)

Vậy x=\(\dfrac{45}{7}\)

\(c,1\dfrac{2}{5}x+\dfrac{3}{7}=\dfrac{-4}{5}\)

\(\dfrac{7}{5}x+\dfrac{3}{7}=\dfrac{-4}{5}\)

\(\dfrac{7}{5}x=\dfrac{-4}{5}-\dfrac{3}{7}\)

\(\dfrac{7}{5}x=\dfrac{-43}{35}\)

\(x=\dfrac{-43}{35}:\dfrac{7}{5}\)

\(x=\dfrac{-43}{49}\)

Vậy x=\(\dfrac{-43}{49}\)

\(d,\left|x+\dfrac{2}{3}\right|+2=2\dfrac{1}{3}\)

\(\left|x+\dfrac{2}{3}\right|+2=\dfrac{7}{3}\)

\(\left|x+\dfrac{2}{3}\right|=\dfrac{7}{3}-2\)

\(\left|x+\dfrac{2}{3}\right|=\dfrac{1}{3}\)hoặc \(x=\dfrac{-1}{3}\)

TH1:\(x+\dfrac{2}{3}=\dfrac{1}{3}\)

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

\(x=-\dfrac{1}{3}\)

TH2:\(x+\dfrac{2}{3}=-\dfrac{1}{3}\)

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

\(x=-1\)

Vậy \(x=\dfrac{-1}{3}\)hoặc \(x=-1\)