$(\sqrt{2,5} + 4 .2,15) - 9. 7/6$
=$\sqrt{2,5} + 8,3-21/2$
=$\sqrt{2,5} + 8,3-10,5$
=$\sqrt{2,5} -2,2$
=$\sqrt{5/2} - 2,2=\dfrac{\sqrt{10}}{2} - 11/5 = \dfrac{5\sqrt{10}-22}{10}
= $\dfrac{40\sqrt{10}-88}{80}$
Ta lai co $9/16 = 45/80$
Ta so sanh $40\sqrt{10}-88$ voi 45.
Hay so sanh $40\sqrt{10}-88$$ voi $133-88$
Ta co $(40\sqrt{10})^2 = 1600.10 = 16000$ va $133^2 = 17689$
Vay $133>40\sqrt{10}$ hay [√2,5+4√(-2.15 ) ^2 ]-(3.√7/6 )^ 2.√1 > 9/16.
