Question
Question: The expression y = ax<sup>2</sup> + bx + c has always the same sign as c if –...
The expression y = ax2 + bx + c has always the same sign as c if –
A
4ac < b2
B
4ac > b2
C
ac < b2
D
ac > b2
Answer
4ac > b2
Explanation
Solution
y = ax2 + bx + c, y(0) = c
So, when c > 0, y > 0, & when c < 0, y < 0
D = b2 – 4ac < 0