题目内容
(1)-42÷(-2)3+1÷(-
)3
(2)(-125
)÷(-5)-2.5÷
×(-
)
(3)(8xy-x2+y2)-3(-x2+y2+5xy)
(4)x-
=
-1
(5)
-
=1.
1 |
2 |
(2)(-125
5 |
7 |
5 |
8 |
1 |
4 |
(3)(8xy-x2+y2)-3(-x2+y2+5xy)
(4)x-
1-x |
3 |
x+2 |
6 |
(5)
0.2x+1 |
0.3 |
0.02x+0.1 |
0.07 |
(1)-42÷(-2)3+1÷(-
)3
=-16÷(-8)+1÷(-
)
=2-8
=-6;
(2)(-125
)÷(-5)-2.5÷
×(-
)
=25
-
×
×(-
)
=25
+1
=26
;
(3)(8xy-x2+y2)-3(-x2+y2+5xy)
=8xy-x2+y2+3x2-3y2-15xy
=2x2-2y2-7xy;
(4)x-
=
-1,
6x-2(1-x)=x+2-6,
6x-2+2x=x+2-6,
7x=-2,
x=-
;
(5)
-
=1,
+
=1,
7(2x+10)+3(2x+10)=21,
14x+70+6x+30=21,
20x=-79,
x=-3.95.
1 |
2 |
=-16÷(-8)+1÷(-
1 |
8 |
=2-8
=-6;
(2)(-125
5 |
7 |
5 |
8 |
1 |
4 |
=25
1 |
7 |
5 |
2 |
8 |
5 |
1 |
4 |
=25
1 |
7 |
=26
1 |
7 |
(3)(8xy-x2+y2)-3(-x2+y2+5xy)
=8xy-x2+y2+3x2-3y2-15xy
=2x2-2y2-7xy;
(4)x-
1-x |
3 |
x+2 |
6 |
6x-2(1-x)=x+2-6,
6x-2+2x=x+2-6,
7x=-2,
x=-
2 |
7 |
(5)
0.2x+1 |
0.3 |
0.02x+0.1 |
0.07 |
2x+10 |
3 |
2x+10 |
7 |
7(2x+10)+3(2x+10)=21,
14x+70+6x+30=21,
20x=-79,
x=-3.95.
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