Question

giúp mình với ạ:'(

Answer 1

b: \(\Leftrightarrow6x^3-8x^2-5x=0\)

\(\Leftrightarrow x\left(6x^2-8x-5\right)=0\)

\(\Leftrightarrow x\in\left\{0;\dfrac{4+\sqrt{46}}{6};\dfrac{4-\sqrt{46}}{6}\right\}\)

c: \(\dfrac{1}{x+1}-\dfrac{5}{x-2}=\dfrac{15}{\left(x+1\right)\left(2-x\right)}\)

\(\Leftrightarrow x-2-5x-5=-15\)

=>-4x-7=-15

=>-4x=-8

hay x=2(loại)

d: \(\Leftrightarrow\dfrac{x+5}{x\left(x-5\right)}-\dfrac{x-5}{2x\left(x+5\right)}=\dfrac{x+25}{2\left(x-5\right)\left(x+5\right)}\)

\(\Leftrightarrow2\left(x+5\right)^2-\left(x-5\right)^2=x\left(x+25\right)\)

\(\Leftrightarrow2x^2+20x+50-x^2+10x-25=x^2+25x\)

=>30x+25=25x

=>5x=-25

hay x=-5(loại)