Question

A line has a slope of -2 and contains the points (3, 5) and (4, y). The value of y is

Answer 1

`\sf{Slope =(y_2-y_1)/(x_2-x_1)`

The slope is -2.
We have two points. (3,5) and (4,y)

Plug it in and solve for y.


`-2 =(y -5)/(4-3) \\\\-2 =(y-5)/(1)\\\\-2 =y -5\\\\y -5 = -2\\\\y -5 + 5 = -2 + 5\\\\y = -2 + 5\\\\\boxed{\bf{y=3}}`

The value of y is 3.

Answer 2

If you are given two points and a line passes through it, use the two point slope form. Let us denote m as -2, x1 as 3, x2 as 4, y1 as 5 and y2 as y. However, in this problem, the y in the second point is unknown. And so you will use the slope formula.

m (slope) = y2 - y1/x2 – x1
-2 = y – 5/4 – 3
-2 = y – 5/1
y – 5 = -2
y = -2 + 5
y = 3