Think of the point (-3,0) and imagine it's the centre of a bicycle wheel. Think of the spokes of the wheel and, for the sake of illustration, imagine every one of them goes through the centre of the wheel. How many spokes? How many spokes could there be? If all the spokes were very thin, there would be many, many spokes. Each spoke is a straight line. So each spoke would be like a linear equation, one for each spoke. How many equations? Countless numbers. y=ax+b is the standard form for a linear equation. Put y=0 and x=-3: 0=-3a+b, so b=3a. Therefore y=ax+3a=a(x+3), where a is any number. So this equation passes through the point (-3,0). There are an infinite number of values for a, so there are an infinite number of lines, an infinite number of spokes. A few examples are y=x+3; y=-x-3 or x+y+3=0; y=2x+6; y=10x+30; y=(x/3)+1;...