问题
解答题
先化简，再求值：(3x+7)(3x-7)-2x(
|
答案
(3x+7)(3x-7)-2x(
x+1)，9 2
=9x2-49-9x2-2x，
=-2x-49，
当x=-6时，原式=-2×（-6）-49，
=12-49，
=-37．
搜题请搜索小程序“爱下问搜题”
先化简，再求值：(3x+7)(3x-7)-2x(
|
(3x+7)(3x-7)-2x(
x+1)，9 2
=9x2-49-9x2-2x，
=-2x-49，
当x=-6时，原式=-2×（-6）-49，
=12-49，
=-37．
| 句子补妆：根据上下文，选择恰当的选项补全对话，使对话完整。 | |
Sarah: 1___________________________ Betty: It's blue and white. Sarah: Wow, it's a cat in the schoolbag. 2___________________________ Betty: Thank you. Sarah: 3___________________________ What's in it? Betty: Many books and pencils. Sarah: 4___________________________ Betty: Sure. 5___________________________ |