An operation* is defined on a set of real number R such that if a,b,E,R,then a*b=a+b-ab determine:2*-1,6*1,5*4

a*b=a+b-ab

I will do the first one, you do the others
fin 2*-1
so your a=2, b=-1

a*b=a+b-ab
= 2 + (-1) - (2)(-1)
= 2 - 1 + 2
= 3