f(0)=2*0-5=-5;
f(-1,5)=2*(-1,5)-5=-8;
f(x)=18-->2x-5=18
2x=23;
x=23/2=11,5;
f(x)=0--->2x-5=0
2x=5;
x=5/2=2,5;
f(0)=2*0-5=-5;
f(-1,5)=2*(-1,5)-5=-8;
f(x)=18-->2x-5=18
2x=23;
x=23/2=11,5;
f(x)=0--->2x-5=0
2x=5;
x=5/2=2,5;