(1) - 390° (2) 30° (3) 690°
A. (1)only B.(1)and(2)only C.(1) and (3)only D. (1),(2),(3)
2.The minimum value of 9^ (2cos^2 x - 1) is
A.-9 B.1/9 C.1 D.9
3.If y = 4x+4, which of the following is true?
(1) y varies directly as x
(2) y varies directly as (x+1)
(3) y is partly constant and partly varies directly as x.
A.(3)only B.(1) and (2)only. C.(2)and (3) only
D.(1),(2),(3)
更新1:
4.Given that the length and the width of a rectangle are (x + 2) cm and x cm respectively. The square of the half of its perimeter is equal to the sum of the squares of its length and width. How many different rectangle(s) can be formed according to the above conditions? A.0 B.1 C.2 D.3
更新2:
5. If (x + y) varies directly as (1/x +1/y), then which of the following is true? A.y varies directly as square root of x. B.y varies directly as x^2. C.y varies directly as 1/x^2 D.y varies directly as 1/x
