ok idk how to use all the math terms and all but the geist it this. since f(x) is strictly increasing, for a<="" f(b)="" is="" always="" true,="" then="" we="" use="" f(a)="" and="" as="" the="" input="" for="" f-1(x),="" which="" gives="" us="" outputs="" of="" a="" b="" respectively.="" since="" its="" already="" established="" that="" a <="" div="">