ce mcq maths

8)

α , β are the roots of 3x² - hx - b = 0

α + β = (- -h) / 3 = h/3

Answer : (C)



11)

275°......十 A
..........∕ 75°
十 B


180 + 75 = 225°

Answer : (E)


12)

Let a be the 1st term , r be the common ratio :

a / (1 - r) = 81/4
a = (81/4)(1 - r) .....(1)

ar = - 9 .....(2)


Sub (1) into (2) :

(81/4)(1 - r) r = - 9

9(r - 1)r = 4

9r² - 9r - 4 = 0

(3r - 4)(3r + 1) = 0

r = 4/3 (rejected since - 1 < r < 1) or r = - 1/3

Answer : (A)




2011-07-24 19:30:24 補充：
Q11) Typing error :

275° should be 255°

2011-07-24 19:31:05 補充：
and 225° should be 255°