Question

计算下列各式,请观察比较所得的结果有什么异同,总结规律

(1)(x+1)(x+4)=x^2+_____x+_____;
(2)(x+4)(x-5)=x^2+_____x+______;
(3)(x-3)( x-4)=x^2+_____x+______;
(4)(x+6)(x-1)=x^2+_____x+______。
总结规律————————————————————————

Answer 1

(1)(x+1)(x+4)=x^2+_5_x+___4__;
(2)(x+4)(x-5)=x^2+__-__x+__-20__;
(3)(x-3)( x-4)=x^2+_-7_x+__12__;
(4)(x+6)(x-1)=x^2+_5_x+__-6__。
总结规律—(x+a)(x+b)=x^2+(a+b)x+ab—