Q. 9

# If the diagram in Fig. 2.22 shows the graph of the polynomial f (x) = ax2 + bx + c, thenA. a > 0, b<0 andc > 0B. a < 0, b <0 and c< 0C. a < 0, b > 0 and c > 0D. a < 0, b > 0 and c < 0

As seen from the graph,

The parabola cuts the graph at two points on the positive x-axis.

Hence, both the roots are positive.

Now, for a polynomial, the sum of roots is given as:

α + β = -b/a

the sum will be positive as the roots are positive.

Also, the product of roots = c/a has to be positive too.

a is positive.

Now, since a is positive, therefore for the sum of roots to be negative, b has to be negative.

a > 0, b< 0 & c > 0.

Therefore, option (a) is correct.

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