Question

Write an equation for the function that includes the points (-2,3) and (-1,9)

Answer 1

y = 6x + 15.

Explanation:

The slope of the line joining these 2 points =

(9-3)/(-1-(-2))

= 6/1

= 6

Use the point-slope form of a straight line:

y - y1 =m(x - x1) Here m = 6 and (x1, y1) will be (-2, 3), so:

y - 3 = 6(x -(-2))

y - 3 = 6(x + 2)

y = 6x + 12 + 3

y = 6x + 15.

Answer 2

f(x)=6x+15

Explanation:

first you find the gradient of the equation with the gradient formula by using the two given points

the gradient is 6, so using the slope equation which is y=mx+b sub 6 into the gradient

you then get y=6x+b

to find b just sub in any of the points and solve the equation.

ps. f(x) essentially stands for a y so don't get confused

hope this helps :)