问题
解答题
已知A=x2-7x-2,B=-2x2+4x-九.求:(九)A-B;(2)2A+3B.
答案
(1)A-B=(x2-7x-2)-(-2x2+4x-1),
=x2-7x-2+2x2-4x+1,
=4x2-11x-1;
(2)2A+4B=2(x2-7x-2)+4(-2x2+4x-1),
=2x2-14x-4-6x2+12x-4,
=-4x2-2x-7.
已知A=x2-7x-2,B=-2x2+4x-九.求:(九)A-B;(2)2A+3B.
(1)A-B=(x2-7x-2)-(-2x2+4x-1),
=x2-7x-2+2x2-4x+1,
=4x2-11x-1;
(2)2A+4B=2(x2-7x-2)+4(-2x2+4x-1),
=2x2-14x-4-6x2+12x-4,
=-4x2-2x-7.