Education Quality And Accountability Office (EQAO) Grade 9 Practice Exam

The key idea is that a line through two points is determined by its slope. First find how steep the line is by calculating the slope: m = (y2 − y1) / (x2 − x1). With that slope, use one of the points in the point-slope form: y − y1 = m(x − x1). If you want the slope-intercept form, solve that for y to get y = mx + b, and use b = y1 − m x1 to find the intercept. For example, with points (1, 2) and (3, 8): m = (8 − 2) / (3 − 1) = 6/2 = 3. Then y − 2 = 3(x − 1) leads to y = 3x − 1. This approach directly uses the two given points to define the line. Plotting a line through the midpoint doesn’t fix its direction, since many lines pass through that point with different slopes. Solving for the y-intercept first isn’t straightforward without knowing the slope. Forming a system to solve for x and y isn’t needed because those coordinates are already known.