Question

how can I find the y intercept if I can't read it directly from the graph because its an improper fraction and/out of view on my limited view of the graph? Two points on exact grid lines: (-2, -7) (-1, -3)

Answer 1

Find the line through the two points and evaluate it at x = 0.

1. Slope: m = (y2 − y1)/(x2 − x1) = (−3 − (−7))/(−1 − (−2)) = 4/1 = 4.
2. Use y = mx + b and plug one point, e.g. (−1, −3): −3 = 4(−1) + b → −3 = −4 + b → b = 1.

So the y‑intercept is (0, 1) and the line is y = 4x + 1.

Quick mental check: from x = −1 to x = 0 is +1 in x; slope 4 means y increases by 4, so −3 + 4 = 1.