Question

Which equation models a line that is perpendicular to y = x - 1 and goes through the point (5,4)

Answer 1

y = - x + 9

Explanation:

Because the line is perpendicular, the slope with be the opposite reciprocal. So, if the slope is 1 as in the equation y = x - 1, the opposite reciprocal is -1.

So the equation that is perpendicular will look like this so far:

y = -x + b (b represents our y-intercept that we have not found yet)

Now we will find the y-intercept. We can find it by substituting the coordinates (5,4) as x and y into the equation right above ^^.

So, 4 = -(5) +b or 4 = -5 + b

Add 5 to both sides to isolate b on the right side. b = 9

Therefore, the y-intercept is 9.

Now we have found everything we need for the equation, which is

y = - x + 9