Question

tim x biet :

a) ( 2x²+4 ) - (x²-3/2 ) = (-3+4x²)+ ( -4x²/3+1)

b) ( I xI -4) - ( 2- I-xI ) = 1/3 . I xI -5

Answer 1

a: \(\Leftrightarrow2x^2+4-x^2+\dfrac{3}{2}=-3+4x^2-\dfrac{4}{3}x^2+1\)

\(\Leftrightarrow x^2+\dfrac{11}{2}=\dfrac{8}{3}x^2-2\)

\(\Leftrightarrow x^2\cdot\dfrac{-5}{3}=-\dfrac{15}{2}\)

\(\Leftrightarrow x^2=\dfrac{9}{2}\)

hay \(x\in\left\{\dfrac{3\sqrt{2}}{2};-\dfrac{3\sqrt{2}}{2}\right\}\)

b: \(\Leftrightarrow\left|x\right|-4-2+\left|x\right|-\dfrac{1}{3}\left|x\right|+5=0\)

\(\Leftrightarrow\left|x\right|\cdot\dfrac{5}{3}=1\)

hay \(x\in\left\{\dfrac{3}{5};-\dfrac{3}{5}\right\}\)