Question

数学七年级

完全平方公式
(2x+5y)²=
(1/5x+1/10y)²=
(1/3m-1/2)²=
(7ab+2)²=
(-2t-1)²=
(-cd+1/2)²=
利用整式乘法公式计算：
96²=
(a-b-3)(a-b+3)=
要过程

Answer 1

(2x+5y)²=4x²+20xy+25y²
(1/5x+1/10y)²=1/25x²+1/25xy+1/100y²
(1/3m-1/2)²=1/9m²-1/3m+1/4
(7ab+2)²=49a²b²+28ab+4
(-2t-1)²=4t²+4t+1
(-cd+1/2)²=c²d²-cd+1/4
利用整式乘法公式计算：
96²=(100-4)²=100²-800+16=9216
(a-b-3)(a-b+3)
=[(a-b)-3][(a-b)+3]
=(a-b)²-9
=a²-2ab+b²-9

Answer 2

a=x-1
x=a+1
则f(a)=2sin[2(a+1)-1]=2sin(2a+1)
所以g(x)=f(x)-1=2sin(2x+1)-1
-1<=sin(2x+1)<=1
-2<=2sin(2x+1)<=2
-3<=2sin(2x+1)-1<=1
所以g(x)值域[-3,1]