plant trees ______
若无穷数列满足:只要,必有,则称具有性质.
(Ⅰ)若具有性质,且,,,,,求;
(Ⅱ)若无穷数列是等差数列,无穷数列是公比为正数的等比数列,,,判断是否具有性质,并说明理由;
(Ⅲ)设是无穷数列,已知求证:“对任意,都具有性质”的充要条件为“是常数列”.
函数的部分图像如图所示,则( )
函数,,记为的从小到大的第个极值点.
(I)证明:数列是等比数列;
(II)若对一,恒成立,求的取值范围.
For investors who desire low risk and guaranteed income, U.S. government bonds are a secure investment because these bonds have the financial backing and full faith and credit of the federal government. Municipal bonds, also secure, are offered by local governments and often have (1) ______ such as tax-free interest. Some may even be (2) ______. Corporate bonds are a bit more risky.
Two questions often (3) ______ first-time corporate bond investors. The first is "If I purchase a corporate bond, do I have to hold it until the maturity date?" The answer is no. Bonds are bought and sold daily on (4) ______ securities exchanges. However, if you decide to sell your bond before its maturity date, you're not guaranteed to get the face value of the bond. For example, if your bond does not have (5) ______ that make it attractive to other investors, you may be forced to sell your bond at a (6) ______, i.e., a price less than the bond's face value. But if your bond is highly valued by other investors, you may be able to sell it at a premium, i.e., a price above its face value. Bond prices generally (7) ______ inversely (相反地)with current market interest rates. As interest rates go up, bond prices fall, and viceversa(反之亦然).Thus, like all investments, bonds have a degree of risk.
The second question is "How can I (8) ______ the investment risk of a particular bond issue?" Standard & Poor's and Moody's Investors Service rate the level of risk of many corporate and government bonds. And (9) ______, the higher the market risk of a bond, the higher the interest rate. Investors will invest in a bond considered risky only if the (10) ______ return is high enough.
A) advantages B) assess C)bother D)conserved E)deduction F) discount G)embarrass H) features I) fluctuate J) indefinite K) insured L) major M) naturally N) potential O) simultaneously |