well, increase could mean it has a positive slope
1 way is to find the slope
y=mx+b
m=slope
so given
f(x)=x-7
y=1x-7
1>0
it is positive so it increasese
the easier way is
if it increases then if x increases then y will increase as well
test some points
if x=1, y=-6
if x=2, y=-5
x increased and y increased
it is an increasing function
