已知a+b=5,a-c=4,求(b+c)^2+2b-1+2c的值 急~~~
问题描述:
已知a+b=5,a-c=4,求(b+c)^2+2b-1+2c的值 急~~~
答
(a+b)-(a-c)=b+c=5-4=1
(b+c)^2+2b-1+2c
=(b+c)^2+2(b+c)-1
=1^2+2-1
=2