WAEC Mathematics 2017 Paper

Concept:The gradient of a line through two points measures its steepness using the change in $y$ divided by the change in $x$.Explanation:Let the first point be $(x_1, y_1) = (-1, 1)$.Let the second point be $(x_2, y_2) = (2, -2)$.The formula for the gradient is:$$m = \frac{y_2 - y_1}{x_2 - x_1}$$Substitute the given values into the formula:$$m = \frac{-2 - 1}{2 - (-1)}$$Simplify the numerator:$$-2 - 1 = -3$$Simplify the denominator:$$2 - (-1) = 2 + 1 = 3$$So the gradient becomes:$$m = \frac{-3}{3} = -1$$Therefore, the gradient of the line joining the two points is $-1$.Answer:The correct option is A. $-1$