合并同类项》
班级 姓名 __ ___
1.判断是不是同类项？对于不是同类项的，能口答说出原因。
(1)3x2y与–3x2y (2)0.2a2b与0.2ab2 (3)11abc与9bc
(4)3m2n3与– n3m2 (5)4xy2z与4x2yz (6)62与x2
2.写出–![](https://wkrtcs.bdimg.com/rtcs/image?w=7&md5sum=c9916491dbf5b9c3dcdd0db83e0deffe&sign=ce794629d8&rtcs_flag=1&rtcs_ver=3.2&l=webapp&bucketNum=20&ipr={"t":"img","w":"7","h":"36","dataType":"gif","c":"word/media/image1.png"})
a²b³c²的三个同类项 、 、 。
3.合并下列多项式中的同类项：
（1）3x2+(–2x2) （2）–a2b –7a2b (3) – 6x2y+6x2y
4.如果2x2ym与–3xny是同类项，那么m=________,n=_________。
5.下列各组中的两项不是同类项的是（ ）
A、2x2y3与–3x2y3 B、10a3b2c与10a2b3c C、5xy与yx D、–![](https://wkrtcs.bdimg.com/rtcs/image?w=15&md5sum=c9916491dbf5b9c3dcdd0db83e0deffe&sign=ce794629d8&rtcs_flag=1&rtcs_ver=3.2&l=webapp&bucketNum=20&ipr={"t":"img","w":"15","h":"41","dataType":"gif","c":"word/media/image2.png"})
和2
6．合并下列各式中的同类项：
① –![](https://wkrtcs.bdimg.com/rtcs/image?w=8&md5sum=c9916491dbf5b9c3dcdd0db83e0deffe&sign=ce794629d8&rtcs_flag=1&rtcs_ver=3.2&l=webapp&bucketNum=20&ipr={"t":"img","w":"8","h":"37","dataType":"gif","c":"word/media/image3.png"})
a –a ②x3y2 –x3y2
③![](https://wkrtcs.bdimg.com/rtcs/image?w=8&md5sum=c9916491dbf5b9c3dcdd0db83e0deffe&sign=ce794629d8&rtcs_flag=1&rtcs_ver=3.2&l=webapp&bucketNum=20&ipr={"t":"img","w":"8","h":"37","dataType":"gif","c":"word/media/image6.png"})
ab³ + 0.2 b³a ④–a2 +a2 –a2
7.若 n为正整数，已知三个连续奇数的中间一个数是2n+1，求这三个连续奇数的和；
如果用2n表示三个连续偶数中的最后一个数，求这三个连续偶数的和。
8. 如果– x a y2与3x5yb–1的和仍是一个单项式，分别求出a+b的值。
9.合并同类项：① 3mn – 5mn + 10mn ② 2abc – bac + ![](https://wkrtcs.bdimg.com/rtcs/image?w=8&md5sum=c9916491dbf5b9c3dcdd0db83e0deffe&sign=ce794629d8&rtcs_flag=1&rtcs_ver=3.2&l=webapp&bucketNum=20&ipr={"t":"img","w":"8","h":"37","dataType":"gif","c":"word/media/image8.png"})
acb
③ x2 – 2xy – 4y2 + 2xy ④ 2(x –2y)² + (x –2y)²
⑤– 3(a+b)2 – 4(a+b)2 ⑥2am+1– am+1 + 5 am+1
10、合并下列多项式中的同类项：
（1）![](https://wkrtcs.bdimg.com/rtcs/image?w=179&md5sum=c9916491dbf5b9c3dcdd0db83e0deffe&sign=ce794629d8&rtcs_flag=1&rtcs_ver=3.2&l=webapp&bucketNum=20&ipr={"t":"img","w":"179","h":"21","dataType":"gif","c":"word/media/image9.png"})
； （2）；
（3）![](https://wkrtcs.bdimg.com/rtcs/image?w=229&md5sum=c9916491dbf5b9c3dcdd0db83e0deffe&sign=ce794629d8&rtcs_flag=1&rtcs_ver=3.2&l=webapp&bucketNum=20&ipr={"t":"img","w":"229","h":"21","dataType":"gif","c":"word/media/image11.png"})
；
11、先化简，再求值：
（1）![](https://wkrtcs.bdimg.com/rtcs/image?w=200&md5sum=c9916491dbf5b9c3dcdd0db83e0deffe&sign=ce794629d8&rtcs_flag=1&rtcs_ver=3.2&l=webapp&bucketNum=20&ipr={"t":"img","w":"200","h":"21","dataType":"gif","c":"word/media/image12.png"})
，其中
（2）已知![](https://wkrtcs.bdimg.com/rtcs/image?w=40&md5sum=c9916491dbf5b9c3dcdd0db83e0deffe&sign=ce794629d8&rtcs_flag=1&rtcs_ver=3.2&l=webapp&bucketNum=20&ipr={"t":"img","w":"40","h":"41","dataType":"gif","c":"word/media/image14.png"})
，y= -2，求代数式的值
12、 合并下列各式中的同类项：
（1）![](https://wkrtcs.bdimg.com/rtcs/image?w=197&md5sum=c9916491dbf5b9c3dcdd0db83e0deffe&sign=ce794629d8&rtcs_flag=1&rtcs_ver=3.2&l=webapp&bucketNum=20&ipr={"t":"img","w":"197","h":"23","dataType":"gif","c":"word/media/image16.png"})
（2）
（3）3 (a+b)+2 (a+b)– 4 (a+b) （4）3 (a+b)2+2 (a+b)– 4 (a+b) 2+2 (a+b)
13、有两块长方体形状的木料，一块的长、宽、高分别是a，2a，b，另一块的长、宽、高分别为a，a，b，这两块木料的体积的和是多少？
14、已知｜m–2｜+(m+n)2=0,求4m2–6n2–2mn–2m2+3n2–mn的值。
15、试说明–x2y+3x2–6yx2+7x2y–2x2+3的值与y的取值无关。
16、如果![](https://wkrtcs.bdimg.com/rtcs/image?w=47&md5sum=c9916491dbf5b9c3dcdd0db83e0deffe&sign=ce794629d8&rtcs_flag=1&rtcs_ver=3.2&l=webapp&bucketNum=20&ipr={"t":"img","w":"47","h":"24","dataType":"gif","c":"word/media/image18.png"})
与是同类项，那么= 。
17、当![](https://wkrtcs.bdimg.com/rtcs/image?w=87&md5sum=c9916491dbf5b9c3dcdd0db83e0deffe&sign=ce794629d8&rtcs_flag=1&rtcs_ver=3.2&l=webapp&bucketNum=20&ipr={"t":"img","w":"87","h":"21","dataType":"gif","c":"word/media/image21.png"})
时，求的值。
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