Question

plzz help me in doing this question given in the picture

Answer 1

The given polynomial is x^3 + 15x^2 + 9x - a.
Let the given polynomial be p(x).
   The divisor given is x + 4
    Let x+4 = 0
   then , x = -4

now , substitute the value of x in p(x)
 we will get  p(-4) =  (-4)^3 + 15 (-4) ^2 + 9(-4) - a
                            = -64 + 240 - 26 - a
                            = 150 - a  ........(1)
we are also given that ,  p(-4) = -80 .........(2)

from (1) and (2) , we get

150 - a = -80
a = 150 +80

a = 230