Question

七年级上册数学 《课时导航》 A4.6 整式的加减(第2课时) 39~40页参考答案

快一点,算了！

Answer 1

1、(x+1)/(x-1)-x²/(x+2)(x+1)
=[(x+1)(x+1)(x+2)-x²(x-1)]/(x-1)(x+1)(x+2)
=[(x²+2x+1)(x+2)-x^3+x²]/[(x-1)(x+2)(x+1)]
=[x^3+2x²+x+2x²+4x+2-x^3+x²]/[(x-1)(x+1)(x+2)]
=[5x²+5x+2]/[(x²-1)(x+2)
=(5x²+5x+2)/(x^3+2x²-x-2)
2、(x+y)/(2x+2y)-(x²+y²)/(x²-y²)
=1/2-(x²+y²)/(x²-y²)
=(x²-y²-2x²-2y²)/2(x²-y²)
=(-x²-3y²)/2(x²-y²)
3、(x+y)/(2x-2y)-(x²+y²)/(x²-y²)
=(x+y)/2(x-y)-(x²+y²)/(x+y)(x-y)
=[(x+y)(x+y)-2(x²+y²)]/[2(x+y)(x-y)]
=(x²+2xy+y²-2x²-2y²]/[2(x+y)(x-y)]
=-(x²-2xy+y²)/[2(x+y)(x-y)]
=-(x-y)²/[2(x+y)(x-y)]
=(y-x)/2(x+y)

Answer 2

A4.6 整式的加减(第2课时)
1.C 2.B 3.C 4.5X-7 5.-10 6.13X-11XY-2Y的2次方 7.1.-3ab-1的2次方=5
2.-6MN+2N+2M 8.答 其中化简后ab的值为9 9.a 10.c 11.20 12.(派r的2次方-2ab)-(派r的2次方-1.5ab)=-0.5ab 13.x=50 14.2=2=4 2=n=2n 6+2=8 6+n=6n 6n-2n=4n 已较多多2n-1个位子 我打了半天选我