How do you write an equation of a line going through (0,7), (3,5)?

2 Answers
Apr 24, 2017

See the entire solution process below:

Explanation:

First, we need to determine the slope of the line going through the two points. The slope can be found by using the formula: m = (color(red)(y_2) - color(blue)(y_1))/(color(red)(x_2) - color(blue)(x_1))

Where m is the slope and (color(blue)(x_1, y_1)) and (color(red)(x_2, y_2)) are the two points on the line.

Substituting the values from the points in the problem gives:

m = (color(red)(5) - color(blue)(7))/(color(red)(3) - color(blue)(0)) = -2/3

Now, we can use the point-slope formula to find an equation going through the two points. The point-slope formula states: (y - color(red)(y_1)) = color(blue)(m)(x - color(red)(x_1))

Where color(blue)(m) is the slope and color(red)(((x_1, y_1))) is a point the line passes through.

Substituting the slope we calculated and the values from the first point gives:

(y - color(red)(7)) = color(blue)(-2/3)(x - color(red)(0))

We can also substitute the slope we calculated and the values from the second point giving:

(y - color(red)(5)) = color(blue)(-2/3)(x - color(red)(3))

We can also solve the first equation for y to transform the equation to slope-intercept form. The slope-intercept form of a linear equation is: y = color(red)(m)x + color(blue)(b)

Where color(red)(m) is the slope and color(blue)(b) is the y-intercept value.

y - color(red)(7) = color(blue)(-2/3)x

y - color(red)(7) + 7 = -2/3x + 7

y - 0 = -2/3x + 7

y = color(red)(-2/3)x + color(blue)(7)

See below.

Explanation:

Since a point is given at (0, 7), you know already that the y - intercept has to be 7. Therefore, you know b in the following equation:

y = mx + b

Now, use the slope formula to find m, the slope.

(7-5)/(0-3) = (2)/(-3)

So the equation must be: y =- 2/3x + 7

Hope that helps!!