1、單項(xiàng)式5a與多項(xiàng)式2a-3b的和是?
5a+2a-3b
=7a-3b;
2、多項(xiàng)式m-n與-2m+6n的差是?
m-n-(-2m+6n)
=m-n+3m-6n
=4m-7n;
3、多項(xiàng)式-3（5x-7y）與6（2x-4y）的和是?
-15x+21y+12x-24y
=-3x-3y;
4、7a-3與3（a-2）的差是?
7a-3-3a+6
=4a+3;
5、化簡：-（x^2-3x+1）+2（x^2+6x-3）的結(jié)果為?
=-x²+3x-1+2x²+12x-6
=x²+15x-7;
6、先化簡,再求值.3x-（-xyz）+（-1/3z^2)-3（x-1/9z^2),其中x=-3,y=-1/6,z=2.
=3x+xyz-z²/3-3x+z²/3
=xyz
=-3×(-1/6)×2
=1;
7、5x^2y-[1/2xy+4(xy^2+1/8xy)-3x^2y].
=5x²y-xy/2-4xy²-xy/8+3x²y
=8x²y-5xy/8-4xy²;
很高興為您解答,skyhunter002為您答疑解惑
如果本題有什么不明白可以追問,