For any quadratic equation y=ax2+bx+c, with roots as α,β such that α<β if a<0&D>0, then select the correct statements.
A
y>0∀x∈(α,β)
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B
y<0∀x∈(−∞,α)
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C
y<0∀x∈(β,∞)
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D
y=0∀x∈{α,β}
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Solution
The correct option is Dy=0∀x∈{α,β} Given the quadratic equation: y=ax2+bx+c with roots α,β such that α<β.
Also, a<0&D>0
Thus, we can draw the general graph of the function as:
Now as from the graph, we can observe: y>0∀x∈(−∞,α)∪(β,∞)&y<0∀x∈(α,β)&y=0∀x∈{α,β}
Thus, all options are correct.