Let the three gp be a, ar and ar^2
a + ar + ar^2 = 21 => a(1 + r + r^2) = 21 . . . (1)
a^2 + a^2r^2 + a^2r^4 = 189 => a^2(1 + r^2 + r^4) = 189 . . . (2)
squaring (1) gives
a^2(1 + r + r^2)^2 = 441 . . . (3)
(3) ÷ (2) => (1 + r + r^2)^2 / (1 + r^2 + r^4) = 441/189 = 7/3
3(1 + r + r^2)^2 = 7(1 + r^2 + r^4)
3(r^4 + 2r^3 + 3r^2 + 2r + 1) = 7(1 + r^2 + r^4)
3r^4 + 6r^3 + 9r^2 + 6r + 3 = 7 + 7r^2 + 7r^4
4r^4 - 6r^3 - 2r^2 - 6r + 4 = 0
r = 1/2 or r = 2
From (1), a = 21/(1 + r + r^2)
When r = 2:
a = 21/(1 + 2 + 4) = 21/7 = 3
Therefore, the numbers are 3, 6 and 12.
Answer:48
Step-by-step explanation:
6*8 shows the c9nbonations of just then 2 together
Answer:
B. 606,900
Step-by-step explanation:
Hope it helps
Answer:
Step-by-step explanation:
the probability that at least one envelope is a yellow envelope is 16/21
Step-by-step explanation:
The probability that at least one envelope is a yellow envelope is P(Y);
P(Y) = 1 - P(Y)'
P(Y)' is the probability that no envelope is a yellow envelope.
Given;
red envelope = 1
blue envelopes = 3
green envelopes = 2
yellow envelopes = 3
Total = 9
Number of non-yellow envelope = 9 -3 = 6(6 envelope are not yellow)
P(Y)' = P1 × P2 × P3
there is no replacement;
P(Y)' = 6/9 × 5/8 × 4/7
P(Y)' = 5/21
From equation 1;
P(Y) = 1 - 5/21
P(Y) = 16/21
the probability that at least one envelope is a yellow envelope is 16/21.
Answer:
Number n increased by 18 = n +18
Number is 2 less than 5 times n= 5n -2
They are same => n +18 = 5n -2
Option B
[ n + 18 = 5n -2
18 +2 =5n - n
20 = 4n
n = 5
Lets check 5+18 = 5*5 - 2
23 = 23]
