In the equation x2 + bx + 12 = 0, x is a variable and b is a constant. What is the value of b ?

(1) x - 3 is a factor of x2 + bx + 12.

(2) 4 is a root of the equation x2 + bx + 12 = 0.

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

EACH statement ALONE is sufficient.

Statements (1) and (2) TOGETHER are NOT sufficient.

##### 考题讲解

（1）  x-3是~$x^2+bx+12=0$~的一个因子，又因为~$x^2$~的系数为1，所以，设另一个因子为(x+k)，则有(x-3)(x+k)=0，展开得~$x^2+(k-3)x-3k=0$~，有-3k=12，解得k=-4，所以b=k-3=-7。题目得解。

（2）4是~$x^2+bx+12=0$~的一个根，将x=4代入解得b=-7。题目得解。