y = 2x + 1 is the equation of a line that passes through (1,3) and (4,9)
Solution:
Given that we have to write the equation of a line that passes through (1,3) and (4,9)
Let us first find the slope of line
The slope of line is given as:

Here the given points are (1,3) and (4,9)

Substituting the values in formula, we get,

Thus slope of line is 2
The equation of line in slope intercept form is given as:
y = mx + c -------- eqn 1
Where, "m" is the slope and "c" is the y - intercept
To find the y intercept, substitute (x, y) = (1, 3) and m = 2 in eqn 1
3 = 2(1) + c
c = 1
Thus the equation of line is:
Substitute c = 1 and m = 2 in eqn 1
y = 2x + 1
Thus equation of line is found