Question

tim x :

( 2x+3)²=9/121

( 3x-1)³=-8/27

 

Answer 1

\(\left(2x+3\right)^2=\frac{9}{121}\)

\(\left(2x+3\right)^2=\left(\frac{3}{11}\right)^2\)

\(\Rightarrow2x+3=\frac{3}{11}\text{ hoặc }2x+3=\frac{-3}{11}\)

\(2x=\frac{3}{11}-3\text{ hoặc }2x=\frac{-3}{11}-3\)

\(2x=\frac{3}{11}-\frac{33}{11}\text{ hoặc }2x=\frac{-3}{11}-\frac{33}{11}\)

\(2x=\frac{-30}{11}\text{ hoặc }2x=\frac{-36}{11}\)

\(x=\frac{-30}{11}:2\text{ hoặc }x=\frac{-36}{11}:2\)

\(x=\frac{-30}{11}.\frac{1}{2}\text{ hoặc }x=\frac{-36}{11}.\frac{1}{2}\)

\(x=\frac{-15}{11}\text{ hoặc }x=\frac{-18}{11}\)