习题11.4第6题答案
解:(a+2a+2.5a)·(1.5a+4.5a) -2a·4.5a+2a·a+a (1.5a+4.5a)
=5.5a·6a-9a2+ 2a2+6a2
=33a2-9ax十2a2+6a2
=32a2(平方厘米)
习题11.4第7题答案
解:(1)原式=2x2 -2xy+4xy-4yx+6x2 +4xy-6xy-4y2 -8x2 +8y2=0
(2)愿式=a2 +ab+2ab+2b2-(a2 -2ab-ab+2bx)+6a2 +2ab- 3ab-b2
=a2+3ab+2b2-a2 +3ab-2b2+6a2-ab-b2=6a2 +5ab-b2
(3)原式=(x3 +2x2+2x2 +4x+2x+4)+(-x3 +5x2 +x-5)
=x3 +2x2+2x2 +4x+ 2x+4 -x3+5x2+x
=5- 9x2 +7x-1
习题11.4第8题答案
解:根据题意,得1/2(a+1) (h-1)= 1/2ah,
化简,得ah-a+h-1=ah,整理,得-a+h-1=0,即h=a+1
习题11.4第9题答案
解:木地板的面积为
4x·2y+3x(x+y)
=8xy+3x2 +3xy
= (3x2 +11xy)平方米;
瓷砖的面积为
2x·x+[4x- (x+y)]·x
= 2x2+(3x- y)·x
= 2x2+3x2-xy
=(5x2-xy)平方米
习题11.4第10题答案
x2 -1 x3 -1 x⁴ -1 xn+1 -1