Question

The equation of the line which has a gradient of 3 and passes through the point (-1,3)

Answer 1

Call the line (d): y = ax + b

(d) intersects the vertical axis at the point where the intersection is 3 ⇒x = 0, y = 3 Instead of (d) we have: b = 3

(d) intersects the horizontal axis at the point where the coordinate is -1 ⇒x = −1, y = 0 Instead of (d) we have: −a + b = 0

Replace into b = 3 into -a + b = 0 we have: −a + 3 = 0⇔a = 3

So the equation for the line is y = 3x + 3

Explanation: