1)An operation* is defined by the relation x*y = 5x + 3y - 4xy

Question

Evaluate i) (2*(-1))

ii) (3*2)*4

Answer 1

A user defined operaator can be treated like a function of two variables, for example,
(i) 2*(-1)
f(x,y)=x*y=5x+3y-4xy
then
2*(-1)
=f(2,-1)
=5(2)+3(-1)-4(2)(-1)
=10-3+8
=15

(ii) (3*2)*4
Evaluate first (3*2) which gives -3.
Then evaluate (-3)*4.