Location of Roots when Compared to two constants 'k1' & 'k2'
If α, β are t...
Question
If α,β are the two roots of the quadratic polynomial f(x)=x2+bax+ca;a≠0. And if exactly one of the roots lies between k1,k2. Then select the correct statements where α,β≠k1,k2 .
A
f(k1)f(k2)>0
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B
f(k1)f(k2)=0
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C
f(k1)f(k2)<0
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D
D>0
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Solution
The correct option is DD>0 Given the quadratic polynomial f(x)=x2+bax+ca;a≠0
Now, given two numbers k1&k2 such that exactly one root lies between k1&k2
The condition can be portrayed as:
Now, from observing we get: A.D>0
Also, from the case k1<α<k2 f(k1)>0&f(k2)<0
And from the case k1<β<k2 f(k1)<0&f(k2)>0
Thus, combining both of them, we get: B.f(k1)f(k2)<0