Question

giúp mình câu 8 với ạ

Answer 1

Bài cúi đúng hem :))

\(\Leftrightarrow\dfrac{4\left(5x^2-3\right)+5\left(3x-1\right)}{20}< \dfrac{10x\left(2x+3\right)-100}{20}\)

\(\Leftrightarrow4\left(5x^2-3\right)+5\left(3x-1\right)< 10x\left(2x+3\right)-100\)

\(\Leftrightarrow20x^2-12+15x-5< 20x^2+30x-100\)

\(\Leftrightarrow-15x< -83\)

\(\Leftrightarrow x>\dfrac{83}{15}\)

Vậy \(S=\left\{x|x>\dfrac{83}{15}\right\}\)

Answer 2

\(8,\dfrac{5x^2-3}{5}+\dfrac{3x-1}{4}< \dfrac{x\left(2x+3\right)}{2}-5\)

\(\Leftrightarrow4\left(5x^2-3\right)+5\left(3x-1\right)< 10x\left(2x+3\right)-100\)

\(\Leftrightarrow20x^2-12+15x-5< 20x^2+30x-100\)

\(\Leftrightarrow20x^2-20x^2+15x-30x-12-5+100< 0\)

\(\Leftrightarrow-15x+83< 0\)

\(\Leftrightarrow-15x< -83\)

\(\Leftrightarrow x>\dfrac{83}{15}\)

Vậy \(S=\left\{x\left|x>\dfrac{83}{15}\right|\right\}\)