Question

Find the equation of the line that passes through the points (1, 6) and (2, 8).

By substitution in this equation, show that (3, 10) also lies on this line.

Answer 1

y = 2x + 4

Explanation:

y2 - y1/ x2- x1

= 8 - 6 / 2 - 1

= 2

So now our equation is y = 2x + b (from y = mx+b). Now plug in the coordinates to find the y-intercept.

y = 2x + b

8 = 2(2) + b

8 = 4 + b

4 = b

The y-intercept is 4.

If we put one of the values like the x in the equation, we should get the y value.

y = 2x + 4

y = 2 (3) + 4

y = 6 + 4

y = 10

(3,10)