JEE Main201815 Apr 2018Evening ShiftMathematicsApplication of DerivativesActual

If f(x) is a quadratic expression such that f(1)+f (2) =0 , and -1 is a root of f(x)=0 , then the other root of f(x)=0 is

Options

A- 5 8
B- 8 5
C5 8
D8 5

Correct answer

D. 8 5

Step-by-step solution

If a and -1 are the roots of the polynomial, then we get aligned & f(x)=x^2+(1-a) x-a . & f(1)=2-2 a and & f(2)=6-3 a As, & f(1)+f(2)=0 & 2-2 a+6-3 a=0 a= 8 5 aligned Therefore, the other root is 8 5

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