Mathematics for IGCSE & O level - Graphs Of Functions (Section 1 - No. 13)
What can be determined about the value of 'a' in the function y = ax² + bx + c if the parabola opens downwards?
a > 0
a < 0
The vertex is a minimum.
The roots are real.
Spiegazione
If the graph opens downwards, a must be negative (a < 0).