2cos^2 x + 3sin x = 0
2(1 - sin^2 x) + 3sin x = 0
2 - 2sin^2 x + 3sin x = 0
2sin^2 x - 3sin x - 2 = 0
Let sin x = m, then
2m^2 - 3m - 2 = 0
2m^2 + m - 4m - 2 = 0
m(2m + 1) - 2(2m + 1) = 0
(m - 2)(2m + 1) = 0
m = 2 or m = -1/2
Now, sin x = -1/2
Therefore, x = 1/6(12nπ - π) and 1/6(12nπ + 7π)
Answer:
1.42 hours
Step-by-step explanation:
In this case we must take into account that the speed would be to fill a pool for a time, that this case is in hours, therefore it would be like this:
1/5 for the first pipe
1/2 for the second pipe
Now, we will use both at the same time, therefore:
1/5 + 1/2 = 1 / x
0.7 = 1 / x
x = 1 / 0.7
x = 1.42
That is to say that if we use both we will take a total of 1.42 hours
54
a rule I follow:
same signs positive,
different signs negative.
-9 * -3 = 27
27 + 27 = 54
