Playing A, B, C
Algebra
Level
4
Let f(x) be a quadratic polynomial with standard notations A, B, C. f(-1) is less than 1. f(1) is greater than -1. f(3) is less than -4 then
A is greater than zero
sign of A can't be predicted
A is less than zero
none of these
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Take a close look in the data given in the question.
f ( − 1 ) < 1 , f ( 1 ) > − 1 & f ( 3 ) < − 4 .
As x increases, the value of f(x) first increases then decreases. This is possible if and only if the co-efficient of x 2 i.e. A is negative .