In solving a problem that reduces to a quadratic equation one student makes a mistake only in the constant term of the equation and obtains 8 and 2 for the roots.

Another student makes a mistake only in the coefficient of the first degree term and finds –9 and –1 for the roots. The correct equation is:

(a) x2 – 10x + 9 = 0

(b) x2 + 10x + 9 = 0

(c) x2 – 10x + 16 = 0

(d) x2 – 8x – 9 = 0