Question

Find the equation of the line shown.

y
10
9
8
5
4
3
2
1
O
1 2 3 4 5 6 7 8 9 10
X

Answer 1

Explanation:

I assume you need the equation in slope-intercept form :

y = ax + b

"a" is the slope, "b" is the y-intercept (the y-value when x = 0).

the slope is defined as ratio (y coordinate change / x coordinate change) when going from one point on the line to another.

let's use the 2 points, where the line intersects the x- and the y- coordinate axis : (0, 9) and (9, 0)

that gives us "b" already : the y-value when x = 0 is 9.

about the slope "a" :

x changes by +9 (from 0 to 9).

y changes by -9 (from 9 to 0).

the slope is then -9/+9 = -1/1 = -1

and the equation is

y = -x + 9