问题
解答题
先化简,再求值.(
|
答案
∵x2+2x-4=0,
∴x(x+2)=4,
∵(
2 |
x-2 |
x-2 |
x2-4x+4 |
x2+2x |
x-2 |
=(
2 |
x-2 |
x-2 |
(x-2)2 |
x-2 |
x(x-2) |
=
2 |
x(x+2) |
1 |
x(x+2) |
1 |
x(x+2) |
∴当x(x+2)=4时,原式=
1 |
x(x+2) |
1 |
4 |
先化简,再求值.(
|
∵x2+2x-4=0,
∴x(x+2)=4,
∵(
2 |
x-2 |
x-2 |
x2-4x+4 |
x2+2x |
x-2 |
=(
2 |
x-2 |
x-2 |
(x-2)2 |
x-2 |
x(x-2) |
=
2 |
x(x+2) |
1 |
x(x+2) |
1 |
x(x+2) |
∴当x(x+2)=4时,原式=
1 |
x(x+2) |
1 |
4 |