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> 在解题目:“当x=1949时,求代数式x2-4x+4x2-4÷x2-2xx+2-1x+1的值”时,聪聪认为x只要任取一个使原式有意义的值代入都有相同结果.你认为他说的有理吗?请说明理由.-数学
在解题目:“当x=1949时,求代数式x2-4x+4x2-4÷x2-2xx+2-1x+1的值”时,聪聪认为x只要任取一个使原式有意义的值代入都有相同结果.你认为他说的有理吗?请说明理由.-数学
题目简介
在解题目:“当x=1949时,求代数式x2-4x+4x2-4÷x2-2xx+2-1x+1的值”时,聪聪认为x只要任取一个使原式有意义的值代入都有相同结果.你认为他说的有理吗?请说明理由.-数学
题目详情
在解题目:“当x=1949时,求代数式
x
2
-4x+4
x
2
-4
÷
x
2
-2x
x+2
-
1
x
+1
的值”时,聪聪认为x只要任取一个使原式有意义的值代入都有相同结果.你认为他说的有理吗?请说明理由.
题型:解答题
难度:中档
来源:巴中
答案
聪聪说的有理.
∵
x
2
-4x+4
x
2
-4
÷
x
2
-2x
x+2
-
class="stub"1
x
+1
=
(x-2)
2
(x+2)(x-2)
×
class="stub"x+2
x(x-2)
-
class="stub"1
x
+1
=
class="stub"1
x
-
class="stub"1
x
+1
=1;
∴只要使原式有意义,无论x取何值,原式的值都相同,为常数1.
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计算:(1)a2+2a+1a2-a-a+1a-1;(2)(-a2
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题目简介
在解题目:“当x=1949时,求代数式x2-4x+4x2-4÷x2-2xx+2-1x+1的值”时,聪聪认为x只要任取一个使原式有意义的值代入都有相同结果.你认为他说的有理吗?请说明理由.-数学
题目详情
答案
∵
=
=1;
∴只要使原式有意义,无论x取何值,原式的值都相同,为常数1.