Question

Draw the graph of y = x² + x and hence solve x² + 1 = 0.

Answer 1

Draw the parabola by the plotting the points (-4, 12), (-3, 6), (-2, 2), (-1, 0), (0, 0), (1, 2), (2, 6), (3, 12), (4, 20), (5, 30)

To solve: x² + 1 = 0, subtract x² + 1 = 0 from y = x² + x. 

x² + 1 = 0 from y = x² + x

Plotting the points (-2, -3), (0, -1), (2, 1) we get a straight line. This line does not intersect the parabola. Therefore there is no real roots for the equation x² + 1 = 0.