2024冀教版七年级下册第八章 整式的乘法课堂练习题及答案8.1 同底数幂的乘法

第八章整式的乘法8.1

同底数幂的乘法第八章整式的乘法同底数幂的乘法

1.计算a2·a的结果为(

)A.a

B.3a C.2a2

D.a32.[2023·石家庄四十二中期末]计算a2·a4的结果是(

)A.a8

B.a6 C.-a8

D.-a6D基础通关B654321879103.计算-(-m2)·(-m)3·(-m)正确的是(

)A.-m3

B.m5C.m6

D.-m64.[2021·河北中考]不一定相等的一组是(

)A.a+b与b+a

B.3a与a+a+aC.a3与a·a·a

D.3(a+b)与3a+bCD65432187910

解:(-10)3×(-10)5=(-10)3+5=(-10)8=108.解:(-8)12×83=812×83=812+3=815.解:xn+1·x2n+1=x(n+1)+(2n+1)=x3n+2.解:a·a5·a7=a1+5+7=a13.654321879106.1光年是光在一年内通过的距离,如果光的速度约为3×105

km/s,一年约为3.2×107s,那么1光年约为多少千米?解:3×105×3.2×107=(3×3.2)×105+7=9.6×1012(km).故1光年约为9.6×1012km.65432187910同底数幂的乘法的逆用7.ym+2可以改写成(

)A.2ym

B.ym·y2

C.ym+2

D.ym+y28.[2023·邯郸期末]若3x=4,3y=6,则3x+y的值是(

)A.24

B.10

C.3

D.12BA65432187910C9.若

·m3=m5,框里应该填的是(

)A.m15

B.m8

C.m2 D.m10.填空:x3·(-x)4·

=x18.

x116543218791011.我们规定:a⊕b=10a×10b,例如,3⊕4=103×104=107,则12⊕3的值为(

)A.1036

B.1015

C.109

D.1012.【易错题】若27×3x=39,则x=

.

13.若2n+2n+2n+2n=26,则n=

.

能力突破B6412111413151614.计算:(1)(x-y)3a·(x-y)2b;(2)(m-2n)3·(m-2n)5;解:(x-y)3a·(x-y)2b=(x-y)3a+2b.解:(m-2n)3·(m-2n)5=(m-2n)3+5=(m-2n)8.121114131516(3)a2·a4+a·a2·a3;(4)(x-y)2(y-x)3(x-y).(结果写成幂的形式)解:a2·a4+a·a2·a3=a2+4+a1+2+3=a6+a6=2a6.解:(x-y)2(y-x)3(x-y)=(x-y)2+1·[-(x-y)3]=-(x-y)3+3=-(x-y)6.12111413151615.已知am=2,an=5,求下列各式的值.(1)-am+2an;(2)(am)3+(an)2;(3)a2(m+n).解:-am+2an=-2+2×5=-2+10=8.

解:a2(m+n)=am+m+n+n=am·am·an·an=2×2×5×5=100.12111413151616.已知a3=m,a5=n,试用含m,n的式子表示2a8+a11.解:2a8+a11=2a3+5+a3+3+5=2a3·a5+a3·a3·a5=2m·n+m·m·n=2mn+m2n.12111413151617.【传统文化】探究:22-21=2×21-1×21=2(

);

23-22=

=2(

);

24-23=

=2(

);

…(1)请仔细观察,写出第4个等式;素养达标1712×22-1×222×23-1×23

2

3解:25-24=2×24-1×24=24.(2)请你找规律,写出第n个等式;(3)计算: