Question

On a coordinate plane, a line passes through points (3,-7) and (-1,9) Write the equation of the line in slope intercept form

Answer 1

First use the slope formula to find the slope of -4.  y2-y1/x2-x1 which looks like this: 9-(-7)/-1-3 = 16/-4 = -4.  Now use that slope and one of the points to sub into the y = mx+b to solve for b and then use that b and your slope of -4 to rewrite the equation.  I chose (-1,9) as my point to get 9=-4(-1)+b.  Solve for b to get b = 5.  Therefore, the equation of the line is y = -4x + 5