Question

tìm x biết

a) \(\frac{-3}{7}+x=\frac{1}{3}\)           b)3/4 +1/4:x=2/5   c)\(1\frac{1}{3}:0,8=\frac{2}{3}:0,1x\)d)|x-3|=1/2           e) \(1\frac{1}{2}.x-4=0,5\)g)\(2^{x-1}=16\)

h)\(\left(x-1\right)^2=25\)i) | 2x-1|=5          k) 0,2-|4,2-2x|=0

Answer 1

a ) \(\frac{-3}{7}+x=\frac{1}{3}\Rightarrow x=\frac{1}{3}-\frac{-3}{7}\Rightarrow x=\frac{16}{21}\)

b) \(\frac{3}{4}+\frac{1}{4}:x=\frac{2}{5}\Rightarrow\frac{1}{4}:x=\frac{2}{5}-\frac{3}{4}\Rightarrow\frac{1}{4}:x=-\frac{7}{20}\Rightarrow x=\frac{1}{4}:\left(-\frac{7}{20}\right)=-\frac{5}{7}\)

c) \(1\frac{1}{3}:0,8=\frac{2}{3}:0,1x\Rightarrow\frac{2}{3}:0,1x=\frac{5}{3}\Rightarrow0,1x=\frac{2}{5}\Rightarrow x=4\)

d) \(\left|x-3\right|=\frac{1}{2}\Rightarrow\orbr{\begin{cases}x-3=\frac{1}{2}\\x-3=-\frac{1}{2}\end{cases}\Rightarrow\orbr{\begin{cases}x=\frac{7}{2}\\x=\frac{5}{2}\end{cases}}}\)

e) \(1\frac{1}{2}.x-4=0,5\Rightarrow\frac{3}{2}x=4,5\Rightarrow x=3\)

g) \(2^{x-1}=16\Rightarrow2^{x-1}=2^4\Rightarrow x-1=4\Rightarrow x=5\)

h) \(\left(x-1\right)^2=25\Rightarrow\orbr{\begin{cases}x-1=5\\x-1=-5\end{cases}\Rightarrow\orbr{\begin{cases}x=6\\x=-4\end{cases}}}\)

i) \(\left|2x-1\right|=5\Rightarrow\orbr{\begin{cases}2x-1=5\\2x-1=-5\end{cases}\Rightarrow\orbr{\begin{cases}x=3\\x=-2\end{cases}}}\)

k) \(0,2-\left|4,2-2x\right|=0\Rightarrow\left|4,2-2x\right|=0,2\Rightarrow\orbr{\begin{cases}4,2-2x=0,2\\4,2-2x=-0,2\end{cases}\Rightarrow\orbr{\begin{cases}x=2\\x=2,2\end{cases}}}\)