1、
a.Factor (2x²- 2)=2(x-1)(x+1),(x²-3x-40)=指枝(x-8)(x+5);
When x=1 or -1,numerator is zero;When x=8 or -5,denominator is zero;
b. The x- intercepts:8 and -5;y-intercept:2;
Vertical asymptotes:x=8 and x=-5;horizontal asymptote:y=f(x)=2;
c. (2x²-2)/(x²-3x-40) > 2;
The detailed process as follows:
If x>8 or x<-5,the inequation degenerate into (2x²-2)>2(x²-3x-40),that is x>-13;
Thus x>8 or -13
inverse function f(y)=(1-5y)/(3y-1);the domain y∈R,y≠绝瞎1/3;Range of f(y):(-∝,5/3)、(5/3,+∝);
3、f(x)= - √(x-3)+1,the domain x≧3;range of f(x)=(-∝,1];
inverse function f(y)=(1-y)²并逗空+3;,the domain x∈R,range of f(y)=[3,+∝);
4、
a. B(t)=12000(1+0.75%)^(4t);
B(10)=12000(1+0.75%)^(4*10)=12000*1.3483=16180.18;
When the account double in value B(t)=24000,(1+0.75%)^(4t)=2,
We can achieve: t=(lg2/lg1.0075)/4=23.19(years)≈23;
b. B(t)=12000(1+0.25%)^(12t);
B(10)=12000(1+0.25%)^(12*10)=12000*1.3494=16192.24;
t=(lg2/lg1.0025)/12=23.13(years)≈23;
【额,你貌似打错了点什么。。。你最好check一下】【另外,其实题很简单啊。。。】
你跟洋人比拼的题不是中文版的那么
我草拿自己的本事比去