Question

What is the equation of the line that goes through (-1,-1) and is perpendicular was to y=5x+3

Answer 1

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

You can use the point-slope form (y - y1 = m(x - x1) by placing the x and y of the point plus the opposite reciprocal of the slope you can easily find that the two lines are perpendicular.