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Q. Let f(x) = ax^2 + bx + c, where a, b and c are certain constants and a nt =0. It is known that f(5) = -3f(2) and that 3 is a root of f(x) = 0

5. What is the other root of f(x) = 0?

(1) -7 (2) -4 (3) 2 (4) 6 (5) Cannot be determined

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putting x=3
9a+3b+c=0
from f(5)=-3f(2)
25a+5b+c=-12a-6b-3c
–>37a+11b+4c=0
als o 36a+12b+4c=0 from f(3)=0 multiplied by 4
–>a-b=0
–>from f(3)=0 we have 12a=-c
–>ax^2+ax-12a=0
–>x^2+x-12=0
–>2nd root=-4

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