If `f: RvecNuu{0},` where `f` (area of triangle joining points `P(5,0),Q(8,4)a n dR(x , y)` such that angle PRQ is a right angle `=` number of triangles, then which of the following is true? `f(5)=4` (b) `f(7)=0` `f(6. 25)=2` (d) `f(x)is into

Answer

5

Explanation

Since `f(|x|)=0` has 8 roots
`implies f(x)=0` has 4 real positive roots but since `f(x)` is polynomial of degree 5
`implies` fifth root is also real.
` :. ` Number of real roots of `f(x)=0` is 5