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4. 下列各组式子中，不是同类项的是(
A.$-mn$与$3mn$
B.$4^3$与$3^4$
C.$m^2n^3$与$n^2m^3$
D.$-0.1m^2n$与$\frac{1}{3}m^2n$
C
)A.$-mn$与$3mn$
B.$4^3$与$3^4$
C.$m^2n^3$与$n^2m^3$
D.$-0.1m^2n$与$\frac{1}{3}m^2n$
答案
4.C
5. 下列说法正确的是(
A.$-0.5x^2y^3$与$2x^3y^2$是同类项
B.$\frac{1}{x}$与$3x$是同类项
C.$\frac{3}{4}xyz$与$\frac{3}{4}xy$是同类项
D.$5a^2b$与$-3ba^2$是同类项
D
)A.$-0.5x^2y^3$与$2x^3y^2$是同类项
B.$\frac{1}{x}$与$3x$是同类项
C.$\frac{3}{4}xyz$与$\frac{3}{4}xy$是同类项
D.$5a^2b$与$-3ba^2$是同类项
答案
5.D
6. 已知单项式$3a^m b^2$与$-2a^4 b^{n-1}$的和是单项式，则$m+n=$
7
。答案
6.7
7. 若单项式$\frac{1}{2}a^{2x}b^m$与$\frac{1}{2}a^n b^{y-1}$可合并为$a^2b^4$，则$xy - mn=$______.
答案
7.-3
8. 单项式$9x^my^2$与单项式$4x^3y^n$是同类项，则$m+n=$
5
.答案
8.5
9. 若单项式$2a^{m}b^{4}$与$-2ab^{2n}$是同类项，则$m-n=$
-1
。答案
9.-1
10. 若$2x^my^3$与$-4xy^n$的和是单项式，则$m+n=$
4
.答案
10.4
11. 已知单项式$x^a y^3$与$-4xy^{4 - b}$是同类项，那么$a - b$的值是
0
.答案
11.0
12. 计算:
(1) $2a^2 - 3a^2 +5a^2$;
(2) $(-b+3a)+(b-a)$;
(3) $5(x^2+2xy)-2(\frac{5}{2}x^2 -xy)$;
(4) $-3x^2y +2x^2y +3xy^2 -2xy^2$;
(5) $-3xy -2y^2 +5xy -4y^2$;
(6) $(x^2 -xy +y^2)-(x^2 -2xy +2y^2)$;
(7) $3x^2 - [6x - (\frac{1}{2}x -3)+2x^2]$;
(8) $x^2 +5y -4x^2 -3y -1$;
(9) $2(3x^2 -2xy)-4(-2x^2 -xy +1)$;
(10) $(5a^2 -2a)-(a^2 -5a +1)$;
(11) $-6ab +ba +8ab$;
(12) $3x^2 - [5x - (\frac{1}{2}x -3)+2x^2]$.
(1) $2a^2 - 3a^2 +5a^2$;
(2) $(-b+3a)+(b-a)$;
(3) $5(x^2+2xy)-2(\frac{5}{2}x^2 -xy)$;
(4) $-3x^2y +2x^2y +3xy^2 -2xy^2$;
(5) $-3xy -2y^2 +5xy -4y^2$;
(6) $(x^2 -xy +y^2)-(x^2 -2xy +2y^2)$;
(7) $3x^2 - [6x - (\frac{1}{2}x -3)+2x^2]$;
(8) $x^2 +5y -4x^2 -3y -1$;
(9) $2(3x^2 -2xy)-4(-2x^2 -xy +1)$;
(10) $(5a^2 -2a)-(a^2 -5a +1)$;
(11) $-6ab +ba +8ab$;
(12) $3x^2 - [5x - (\frac{1}{2}x -3)+2x^2]$.
答案
(1)$4a^2$
(2)$2a$
(3)$12xy$
(4)$-x^2y+xy^2$
(5)$2xy-6y^2$
(6)$xy-y^2$
(7)$x^2-\frac{11}{2}x-3$
(8)$-3x^2+2y-1$
(9)$14x^2-4$
(10)$4a^2+3a-1$
(11)$3ab$
(12)$x^2-\frac{9}{2}x-3$
(2)$2a$
(3)$12xy$
(4)$-x^2y+xy^2$
(5)$2xy-6y^2$
(6)$xy-y^2$
(7)$x^2-\frac{11}{2}x-3$
(8)$-3x^2+2y-1$
(9)$14x^2-4$
(10)$4a^2+3a-1$
(11)$3ab$
(12)$x^2-\frac{9}{2}x-3$
