X^2 + 18x + 7 = 0
x^2 + 18x = -7
x^2 + 18x + 81 = -7 + 81....add 81 to both sides
(x + 9)^2 = 74
x + 9 = sqrt 74
x = -9 (+-) sqrt 74
x = -9 + sqrt 74
x = -9 - sqrt 74
the reason u add 81 to both sides.....u take half of the x term, then square it.
half of 18 is 9....9^2 = 81
Answer:
22:19
Step-by-step explanation:
Matches lose=82-44
=38
ratio=44:38
=22:19
Question has missing details (Full question below)
Measurement error that is continuous and uniformly distributed from –3 to +3 millivolts is added to a circuit’s true voltage. Then the measurement is rounded to the nearest millivolt so that it becomes discrete. Suppose that the true voltage is 219 millivolts. What is the mean and variance of the measured voltage
Answer:
Mean = 219
Variance = 4
Step-by-step explanation:
Given
Let X be a random variable measurement error.
X has a discrete uniform distribution as follows
a = 219 - 3 = 216
b = 219 + 3 = 222
Mean or Expected value is calculated as follows;
E(x) = ½(216+222)
E(x) = ½ * 438
E(x) = 219
Variance is calculated as follows;
Var(x) = ((b-a+1)²-1)/12
Var(x) = ((222-216+1)²-1)/12
Var(x) = (7²-1)/12
Var(x) = 48/12
Var(x) = 4
Answer:
bearing of A from C is - 65.24°
the distance |BC| is 187.84 m
Step-by-step explanation:
given data
girl walks AB = 285 m (side c)
bearing angle B = 78°
girl walks AC = 307 m (side a)
solution
we use here the Cosine Law for getting side b that is
ac² = ab² + bc² - 2 × ab × cos(B) ...............1
307² = 285² + x² - 2 × 285 cos(78)
x = 187.84 m
and
now we get here angle θ , the bearing from A to C get by law of sines
sin (θ) =
sin (θ) = 0.5985
θ = 36.76°
and as we get here angle BAC that is
angle BCA = 180 - ( 36.76° + 78° )
angle BCA = 65.24°
and here negative bearing of A from C so - 65.24°