For what values of m does the graph of y=mx^2-5x-2 have no x-intercepts

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).