Question

Write the equation of the line that passes through (-1, 11) and (3, -5)

Answer 1

y= -4x+7

Explanation:

The equation of a line is usually written in the form of y=mx+c, where m is the gradient and c is the y-intercept.

Let's find the gradient of the line first.

`gradient = (y1 - y2)/(x1 - x2)`

Using the above formula,

`m = (11 - ( - 5))/( - 1 - 3) \\ m = (11 + 5)/( - 4) \\ m = (16)/( - 4) \\ m = - 4`

Susbt. m= -4 into the equation:

y= -4x +c

Subst. a coordinate to find c.

When x=3, y= -5,

-5= -4(3) +c

-5= -12 +c

c= 12 -5

c=7

Thus the equation of the line is y= -4x +7.