A quadratic curve intersects the axes at (–3, 0), (3, 0) and (0, 18). Work out the equation of the curve
Using the equation y = ax2 + bx + cCreate 3 separate equations:-a(3)2 + b(3) + 18 = 0 -a(-3)2 + b(-3) + 18 = 0
-9a+3b = -18-9a - 3b = -18
add the equations:-9a-9a-3b+3b=-18-18-18a = -36a = 2
Substitute a into equation to find b:
-2(9) - 3b = -18b =0
Therefore,
y = -2x2 + 18
