The roots of the polynomial f(x)=7x2+31x+c=0 are reciprocals of each other. What is the value of c?

Answer 1

we know the discriminant d^2 = 961-28c

so, the roots are

(-31 + √(961-28c))/14
and
(-31 - √(961-28c))/14

since they are reciprocals,

(-31 - √(961-28c))/14 = 14/(-31 + √(961-28c))

961-(961-28c) = 196
c = 7

Answer 2

3(x+6)+8x=