how can u tell if a equation is liner?

Answer 1

if you mean linear,

it has a term of the form ax where a is a constant, and it has no higher powers of x.

More generally, it can be written in a variety of forms:

ax+by+c=0
ax+by=c
y=mx+b
y-k = m(x-h)

I'm sure your text covers it in some detail.

Answer 2

thanks steve