Equation in slope-intercept form that contains (4,1) and (-2,-1)

Y = mx + b;

Then, 1 = 4m + b and - 1 = - 2m + b;

b = 1 - 4m;

-1 = - 2m + (1 - 4m);

-1 = - 2m + 1 - 4m;

-1 - 1 = - 6m;

-2 = - 6m;

m = (-2) / ( - 6);

m = 1 / 3;

b = 1 - 4 * (1 / 3);

b = 1 - 4 / 3;

b = - 1 / 3;

y = (1 / 3) x - 1 / 3;