1.有一根竹竿长a米,一条绳子长(a+2b)米(b>1\2a),将绳子对折后,它比竹竿长多少米?
(a+2b)/2-a=b-a/2
2.如果mx²y^n是关于x,y的一个单项式,且系数是3,次数是4,则m=____,n=____
m=3,n=4
3.写出一个次数为5的单项式：______
10x^5
4.若2\3a²b^m与-0.8a^nb^4相加后的结果还是单项式,则m=_____n=______.
m=4,n=2
5.化简先去括号再合并.
(1)5(x-y)+2(x-y)-4(x-y)=____=____
5(x-y)+2(x-y)-4(x-y)=5x-5y+2x-2y-4x+4y=3x-3y
(2)a-(5a-3b)+(2b-a)=____=_____
a-(5a-3b)+(2b-a)=a-5a+3b+2b-a=5b-5a
(3)a-2(5a-3b)+(2b-a)=____=____
a-2(5a-3b)+(2b-a)=a-10a+6b+2b-a=8b-10a
6.若a+3b=2时,则代数式10-a-3b的值为_______
10-a-3b=10-(a+3b)=10-2=8
7.已知m²+m+2的值为5,则代数式2m²+2m-6的值为____
m²+m+2=5,所以m²+m=3,所以2m²+2m-6=2(m²+m)-6=2*3-6=0