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计算:(1)x2y?25x2y?2x2y(2)(3a-2)-3(a+5)(3)(4a2b-5ab2)-(3a2b-4ab2)(4)3x2-[7x-3(4x-
计算:(1)x2y?25x2y?2x2y(2)(3a-2)-3(a+5)(3)(4a2b-5ab2)-(3a2b-4ab2)(4)3x2-[7x-3(4x-3)-2x2].
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第1个回答 2014-09-17
(1)原式=(1-
2
5
-2)x
2
y
=-
7
5
x
2
y;
(2)原式=3a-2-3a-15
=-17;
(3)原式=4a
2
b-5ab
2
-3a
2
b+4ab
2
=a
2
b-ab
2
;
(4)原式=3x
2
-[7x-12x+9-2x
2
]
=3x
2
-7x+12x-9+2x
2
=5x
2
+5x-9.
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计算:(1)5a?
109a3b?6
aba2?4
;
(2)(?
12x4y
)2
÷
(?3x2y)3
;
(3)(a?5)?25
...
答:
(1)原式=5(a?2)9a3b?6ab(a+
2)(
a?2)=10
3a2
(a+2);
(2)
原式=144x8y2÷(-27?x6y2)=-16
3x2y4
;
(3)
原式=-(a-5)
?(a+5)(
a?5)(a?5)2=-(a+5)=-a-5;
(4)
原式=
2(x?2)
x(x+
3)?(x
+
3)2x?2
=2(x+
3)x
.
(1)x
^
2y+2x
y+y=
?
(2)
9x^
2+
12xy+4y^2
(3)
9
(x
-y)^2-12(x-y
)+4
(4)(a
...
答:
=
y(x
²+
2x+1
)=y(x+1)²
(2)
9x^2+12xy+4y^2 =(
3x+2y)
²
(3)
9(x-y)^2-12(x-y)+4 =(3x-3y-2)²
(4)(a+
b)^2+10(a+b)(a-b)+
25(
a-b)^2 =(a+b+5a-5b)²=(6a-4b)²=
4(3a
-
2b)
²
(5)1
+2x+6+(x+3^2 好象有问题 ...
计算
下列各题.
(1)3a2b(
-
4a2b+2ab2
-ab);
(2)
?5x?
(x2y?
xy
2)?2x2(
12xy+...
答:
(1)原式=-12a4b2+6a3b3-3a3b2;
(2)
原式=-5x3y
+5x2y
2-x3y-
2x2y2
=-5x3y+
3x2y2
-x3y.
计算:(1)(
-
4a)?(ab2+3a2b
-1);
(2)(
34x6y2+65x3y5-0.9
x2y
3)÷(-0.6xy...
答:
ab2+(
-
4a)?3a2b+(
-4a)?(-1)=-
4a2b2
-12a3b+4a.
(2)
原式=34x6y2÷(-0.6xy)+65x3y5÷(-0.6xy
)+(
-0.9
x2y
3)÷(-0.6xy)=-54x5y-
2x2y
4+32xy2.
(3)
原式=a3-2a2
+3a
-6-a3+2a2+2a=5a-6.
(4)
原式=4
x2
-4xy+y2-4x2-8xy+4xy+8y2=-8xy+9y2.
(5
...
(1)
1
2x2y(?
2
3x2?
56xy+34y2)
(2)(
2x+7)(2x-7
)-(
3x
+5)(3
-2x
)(3)
x2?x4+...
答:
(-2
3x2)
-1
2x2y?
56xy+12x2y?34y2=-8x4y-10x3y2+9
x2y
3;
(2)
原式=4x2-49-9x+6x2-15+10x=10
x2+x
-64;
(3)
原式=x6+x6-x6=x6;
(4)
原式=1-4+14+14=-52;
(5)
原式=16a4÷(-
4a2)
-8a3÷(-4a2)-4a2÷(-4a2)=-
4a2+
2a+1;(6)解:原式=
[(a
-
2b
...
计算(1)(2x2y)3?(
-
7x
y2)÷(14x4y3)
(2)(
x-
5)2
-(x-2)(
x-3)(3)[(a+
b...
答:
(-7xy2)÷(14x4y3)=-x3y2;
(2)
原式=x2-10x+25-
(x2-5x+
6)=x2-10x+25-
x2+
5x-6=-5x+19;
(3)
原式=(a2-
b2+a2+
2
ab+b2
-2
a2)
÷(-2a)=2ab÷(-2a)=-b;
(4)
原式=
(4a
2-
4a+1
-
4a2+1+
2
a2+3a-2)
÷2a=(2a2-a)÷2a=a-12,当a=12时,原式=12-12=...
3x+2(3x
-
2y)
=
25x+2y
=
3(x+
y)解方程组?
答:
3x+2(3x
-
2y)
=
2 5x+2y
=
3(x+
y)解: 1、 5x+2y=3(x+y)5x+2y=3x+3y 5x-3x=3y-2y
2x
=y 2、 代入y=2x 3x+2(3x-2y)=2 3x+6x-4y=2 9x-4y=2 9x-4×2x=2 9x-8x=2 x=2 3、 y=2x y=2×2 y=4 所以:x=2 y=4 ...
...
1)(
-
2x2)3
-(x3
)2(2)(
5
a2b)(?3a2b
3c2)(?2
5ab2)(3)(?
14
)?1+(?2)2
...
答:
(1)原式=-8x6-x6=-9x6;
(2)
原式=(5×3×
25)a2+2+
1b1
+3+
2c2=6a5b6c2;
(3)
原式=-
4+4
×
1
-4=-4;
(4)
原式=
x2
-
(2y
-
3)2
=x2-4y2+12y-9;
1.
计算
(1) (
5x-
2y)
^
2+
20xy
(2)(x-3)
^
2(x+
3)^2
(3) (3x
-
5)
^2-
(2x+
7...
答:
1.
计算
(1
) (5x-
2y)
^2+20xy =
25x
^2-20xy+4y^2+20xy =25x^2+4y^2
(2)(x-3
)^
2(x+
3)^2 =(x^2-9)^2 =x^4-18x^2+81
(3) (3x
-5)^2-
(2x+
7)^2 =(3x-
5+2x+
7
)(3x
-5-2x-7)=(5x-
2)(x
-12)=5x^2-60x-2x+24 =5x^2-6
2x+
24
(4)(x
...
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