Answer:
3) y = 3x
Step-by-step explanation:
a line equation is typically written as
y = ax + b
a is the slope, the inclination of the line. it is defined as ratio of "y coordinate change / x coordinate change" when going from one point to another on the line.
so, e.g. going from (0,0) to (4,12) means
x changes by +4 (from 0 to 4)
y changes by +12 (from 0 to 12)
so, the slope is +12/+4 = 3
and the line equation starts like this
y = 3x + b
now, b is the y-intercept : the y value, where the line intercepts (crosses) the y-axis. in other words, the y value where x = 0.
and we have that right away, as the line goes through (0,0). that IS the y-intercept point. the y value there is 0.
therefore, b=0.
and so the full line equation is
y = 3x
