10) \(\dfrac{8x+12}{28}\)>\(\dfrac{7x-35}{28}\)

    =>8x+12>x-5 (đpcm)

điều này đúng vs mọi x

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

    =>\(\dfrac{12x}{6}\)-\(\dfrac{2x+6}{6}\)<\(\dfrac{9\left(x-2\right)}{6}\)+\(\dfrac{30}{6}\)-\(\dfrac{6x}{6}\)

=>12x-2x-6<9x-18+30-6x

=>10x-6<3x+12

sai thì thôi nhé

câu 7 đấy

\(\dfrac{20x-20}{5}\)-\(\dfrac{2-x}{15}\)<\(\dfrac{30x-9}{15}\)

=20x-20-2+x<30x-9

=21x-22<30x-9

điều này đúng vs mọi x