– Which of these two books will you take? – I’ll take _________. I need them to kill time on my journey.
A.
either
B.
none
C.
all
D.
both
拍照语音搜题,微信中搜索"皮皮学"使用
参考答案:
参考解析:
知识点:
皮皮学刷刷变学霸
举一反三
【简答题】阅读下面材料: 若设关于x的一元二次方程ax 2 +bx+c=0(a≠0)的两个根为x 1 ,x 2 ,那么由根与系数的关系得:x 1 +x 2 =- b a ,x 1 x 2 = c a .∵ b a =-( x 1 + x 2 ) c a = x 1 x 2 ,∴ a x 2 +bx+c=a( x 2 + b a x+ c a ) =a[x 2 -(x 1 +x 2 )x+x 1 x 2 ]=...