Suppose the quadratic polynomial \( P(x)=a x^{2}+b x+c \) has positive coefficients \( a, b, c \...

Suppose the quadratic polynomial \( P(x)=a x^{2}+b x+c \) has positive coefficients \( a, b, c \) in arithmetic progression in that order. If \( P(x)=0 \) has integer roots \( \alpha \) and \( \beta \), then \( \alpha+\beta+\alpha \beta \) equals
(a) 3
(b) 5
(c) 7
(d) 14