Respuesta :

Consider this option:
according the condition the graph mx²-5x-2 have no x-interception.
It means that D<0:
D=25+2*4*m=25+8m<0; ⇒ 8m+25<0; ⇔ m<-25/8; ⇔ m<-3.125.

answer: m∈(-oo;-3.125).