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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