问题
解答题
(1)解方程组
(2)先化简,再求值:(
|
答案
(1)由①得:y=2x③,
把③代入②得:x+4x=-2,
解得:x=-
2 |
5 |
把x=-
2 |
5 |
4 |
5 |
即原方程组的解为
|
(2)原式=
3x |
x-1 |
(x+1)(x-1) |
2x |
x |
x+1 |
(x+1)(x-1) |
2x |
=
3(x+1) |
2 |
x-1 |
2 |
=
3x+3-x+1 |
2 |
=
2x+4 |
2 |
=x+2
当x=-3时,原式=-3+2=-1.
(1)解方程组
(2)先化简,再求值:(
|
(1)由①得:y=2x③,
把③代入②得:x+4x=-2,
解得:x=-
2 |
5 |
把x=-
2 |
5 |
4 |
5 |
即原方程组的解为
|
(2)原式=
3x |
x-1 |
(x+1)(x-1) |
2x |
x |
x+1 |
(x+1)(x-1) |
2x |
=
3(x+1) |
2 |
x-1 |
2 |
=
3x+3-x+1 |
2 |
=
2x+4 |
2 |
=x+2
当x=-3时,原式=-3+2=-1.