Location of Roots When Compared with a Constant 'k'
The least pos...
Question
The least positive integer value of a for which both roots of the quadratic equation (a2−6a+5)x2+(√a2+2a)x+(6a−a2−8)=0 lie on either side of origin, is -
A
2
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B
1
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C
6
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D
3
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Solution
The correct option is D3 a2+2a≥0⇒a∈(−∞,−2]∪[0,∞)
Since, both the roots lie on either side of the origin.
Product of roots < 0 ca<0 ⇒6a−a2−8a2−6a+5<0 ⇒a2−6a+8a2−6a+5>0 ⇒(a−2)(a−4)(a−1)(a−5)>0
So a∈(−∞,−2]∪[0,1)∪(2,4)∪(5,∞)
So the least positive integer value of a=3