What is the equation of the line that has a slope of 4 and goes through (1,9)?

2 Answers
Oct 22, 2016

y=4x+13

Explanation:

When you are given the slope and a set of points, you use point slope form, which is:

y-y_1=m(x-x_1)

Where m is the slope, y_1 is the y in the set of points, and x_1 is the x in the set of points

So, plug in your numbers

y-9=4(x-1)

Distribute the 4 throughout the set of parenthesis on the right

y-9=4x-4

Begin to isolate y by adding 9 on both sides of the equation

y=4x+5

Oct 22, 2016

The equation in point-slope form is y - 9 = 4(x - 1).

Explanation:

Use the point-slope form of a linear equation, which is
y - y_1 = m(x - x_1)
where m is the slope of the line and (x_1, y_1) is a point on the line.

y - 9 = 4(x - 1)

If the answer needs to be in slope-intercept form, solve the equation for y:

y - 9 = 4(x - 1)
y - 9 = 4x - 4
y - 9 + 9 = 4x - 4 + 9
y = 4x + 5

If the answer needs to be in standard form, continue using inverse operations to take the equation from slope-intercept form to standard form.

y = 4x + 5
-4x + y = 4x - 4x + 5
-4x + y = 5
-1(-4x + y = 5)
4x - y = -5