Question

write a linear function that passes through (1,5) and (2,15)

Answer 1

Simple,

using $\frac{y1-y2}{x1-x2} =m (slope)$

find your slope...

$\frac{5-15}{1-2} = \frac{-10}{-1}=10$

thus, 10=m (slope)

Now, using y=mx+b to find your equation, plug in what you know...

Use any of the 2 coordinates.. (1,5)

5= 10(1)+b

5=10+b
-10 -10

-5=b

Thus, the equation to your line is...

y=10x-5.