Q.

All the values of k for which the quadratic polynomial f(x)=2x2+kx+k2+5 has two distinct zeros and only one of them satisfying 0 < x < 2, lie in the interval (a, b). The value of (a + 10b) is

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answer is 7.

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Detailed Solution

For two distinct roots, D > 0 i.e., k2 + 8(k2 + 5) > 0 which is always true

Also let f(x)=2x2+kx+k2+5=0

But f(0) > 0. So, f(2) < 0

8+2k+k2+5<0 k2+2k3<0 (k+3)(k1)<0k(3,1) a=3;b=1 a+10b=3+10=7

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